Air Capture

March 30th, 2008 by group

The main barrier is the efficiency of the energy requirements during the reducing process. Air capture requires energy to move the air, manufacture the absorbing solutions and solids as well as to produce the oxygen, fuel and make up chemicals. All of these items will result in additional CO2 emissions, which reduce the efficiency and therefore the benefits. The second important consideration, and maybe the dominant one, is cost. Air capture has to be more economical than the proposed alternatives (hydrogen, electricity, renewables, greater efficiency etc.). It should be stated clearly that air capture is not a viable alternative to capture at large, point source emitters such as power plants since it will always be more efficient to capture and store carbon dioxide from more concentrated streams. So while there are any non-CCS fossil fuel plants, Air Capture is a non-starter.

But recent suugestions have re-thought air capture as a thermal process. The early incarnations of air capture used electricity as the energy source and therefore depended on carbon-free sources. A thermal Air Capture system uses heat that can be generated on-site, reducing the inefficiencies associated with producing electricity, but of course it still needs a source of (carbon-free) heat. Notably, this implies that air capture could reduce greenhouse gas emissions independently of developments in the power generation or transportation sector. Preliminary experimentation has shown that causticization can occur at ambient temperatures and that conventional vacuum filtration is sufficient to avoid large evaporation penalties. These developments reduce the total energy required for the process by about half compared to the conventional method and thereby reduce the amount of CO2 that would need to be sent to storage.

However, the cost of air capture is still basically unknown. Estimates have varied wildly and real numbers will only come from pilot projects over the next few years. In some sense, that puts this technology on par with the hydrogen economy with expansion potentially starting sometime after 2015. For now there are far easier (efficiency) and cheaper (power plants) ways of reducing emissions of CO2 and so air capture is not a replacement for other efforts to reduce emissions. But in the long run, all carbon sources will require mitigation – including the transportation sector – and at that time air capture could be the most cost effective option for some sources. It is not any kind of panacea though.

238 comments on this post.

March 30th, 2008 at 4:53 AM

I promised a few months ago that I would post only once in a blue moon about
the ongoing polar cities adaptation strategy project, and since this topic is about adaptation strategies, just a note to say the New York Times posted a brief introduction today to the polar cities idea here:

Nigel Williams:

March 30th, 2008 at 5:05 AM

…and we need to add to the equation the issue of the transport of the captured CO2. Since we are aiming to reduce CO2 faster than we are emitting it we will need to be transporting three to four times the volume of oil used at the time (plus coal cartage, of course) so it appears we are looking at a CO2-free transport system approaching five times the capacity of the global oil transport system to cart the CO2 to its eventual sequestration destination. What does that do to the economics? Not much, I suspect!

dreamin:

March 30th, 2008 at 5:12 AM

Fascinating. Now what about the ARGO measurements?

March 30th, 2008 at 5:32 AM

What is the point of turning the CO2 back into a gas? You then need to store CO2 gas somewhere safe for hundreds of years, which we don’t yet know how to do.

If you are going to go down the path of air capture, serpentine mineral carbonation (a la the UBC group) seems like a much more sensible alternative. There is no net energy cost, the only waste products are silica and water, and the CO2 is stuck in a mineral phase that should be stable on the timescale of civilization.

March 30th, 2008 at 5:49 AM

A fascinating post. Thank you to the RC guys for opening up this area of discussion.

Is there any hope for this: in effect the acceleration of natural CO2 exothermic weathering of rocks, to sequester CO2 or even generate power?

I didn’t understand the reference to an oxygen-fired kiln. How does that work?

Steve Horstmeyer:

March 30th, 2008 at 6:54 AM

As a person who has tried to be as green as possible for decades, (my wife takes public transportation, I ride my bike about half of my commute milage, in winter our thermostat is rarely set above 57°F, 14°C) I am always suspicious of what I call “life goes on as normal” (LGOAN) solutions to environmental problems.

Carbon sequestration/removal in the various proposed forms (air removal, underground storage, using iron filings to seed the ocean, etc.)all only make sense as short-term, emergency measures.
If all the world put forth maximum effort is there enough time and potentially enough carbon removal to make a difference?

I suspect that as governments allocated funds for massive projects politician would sell the project by stressing this is a painless solution and, “yes my constitutents you can now drive you gas gussler guilt free and LGOAN.”

Electric cars are not carbon free, but the source of emissions is centralized making carbon removal of emissions less daunting. Solar panels on all new homes and incentives for installing them on existing homes, along with universal net electrical metering would go a long way to reduce emissions, especially if some the the captured insolation was used to heat water and the home when needed in lieu of fuel oil or natural gas.

Both those solutions have a “corporate” problem. GM killed a fully functional electric commuter car because, I suspect, there was little if any maintainance neededand therefore less money to be made. How much carbon could be eliminated if an electric car targeted at the urban commuter was affordable?

Solar panels on homes have to buck the electric power industry after all they want to sell power not buy it. I live in Ohio and even this state has net metering.

What is needed is a well coordinated attack using all viable means of removing carbon emissions, reducing the emissions of current technologies and switching to new carbon-free technologies.

As the price of gasoline in the U.S. approaches what Europeans have been paying for years the sales of low gas milage SUVs have plunged while, turn on your TV, auto manufacturers spend millions in advertising to convince the buyer they need a 7000 pound (15,400 kg.)vehicle with all the comforts of home.

March 30th, 2008 at 7:09 AM

“It should be stated clearly that air capture is not a viable alternative to capture at large, point source emitters such as power plants since it will always be more efficient to capture and store carbon dioxide from more concentrated streams. So while there are any non-CCS fossil fuel plants, Air Capture is a non-starter.”

This seems rather simplistic, even in an article intended for popular consumption rather than scientific rigour. It only takes a few seconds thought to realise that there are (at least?) two ways in which air capture can have an advantage over CCS at power plants: first, if cheap/renewable energy is available at a site remote from the fossil fuel plants (eg solar-powered air capture could in principle be viable in some sunny but otherwise low-amenity desert region), and second, it could in principle be better to capture at a suitable storage site rather than capture at the emissions site and then transport to a storage site (effectively, we can use the atmospheric circulation to do the transport for free). And maybe both of these advantages could be combined, eg via my patented maintenance-free floating rafts of coconut trees which directly sink their genetically-engineered carbon-heavy fruit to the ocean floor for long-term sequestration (you read it here first, folks).

I’m not suggesting that these possibilities are necessarily so advantageous as to make free air capture a strong contender at this time or even in the near future (in fact I’ve argued against it on Roger Pielke Jnr’s blog), but surely any comparison must be made on the basis of a quantitative accounting for the various costs, not just a dismissive hand-wave.

March 30th, 2008 at 7:12 AM

Are there processes that could sequester air-captured CO2 in durable and economically useful bulk material goods, perhaps in railway cross-ties or something similar, without energy-intensive requirements like prior concentration of the CO2?

Bernie:

March 30th, 2008 at 7:37 AM

This is an extremely disappointing post. How large are these facilities? Exactly where and how will the CO2 be sequestered? Wouldn’t reforesting the Sahara be easier and cheaper?

March 30th, 2008 at 8:32 AM

“One of the central challenges of controlling anthropogenic climate change is developing technologies that deal with emissions from small, dispersed sources such as automobiles and residential houses.”

This is certainly true as far as it goes, but don’t forget that technologies are not the only way of addressing this problem. Social innovations like David Fleming’s TEQs scheme play a major and necessary part in reducing these dispersed emissions, thus reducing the direct technical challenge of atmospheric removal.

Second, the world has a LOT of zero carbon waste heat not currently being used for anything. Indeed, U.S. thermal power plants alone throw away in waste heat as much energy as Japan uses for every purpose! That’s more than 20 quads. And that doesn’t even count the heat thrown away in industrial processes. Now the smartest thing to do with that heat for the next few decades is obviously either generate electricity with it or use it for heating buildings or industrial processes.

But we should surely do a fair amount of research on air capture, since, by not later than the 2020s, we’re going to get desperate for emissions reductions, and by the 2030s, we’re going to be very desperate and willing to pursue expensive options we that aren’t yet politically realistic.

pete best:

March 30th, 2008 at 8:59 AM

If there is no full scale prototype of the technology (one of the broadsheets or sky TV in the UK has mentioned this technology) then it either needs talking up(as do other geoengineering -ve feedbacks such as eliminating 1% of sunlight etc) in order to be demontrated to be viable for when we do not listen to James Hansen and build the non CCS coal fired power stations hat he is trying to eliminate.

March 30th, 2008 at 12:05 PM

Six+ things from me: (see Joe Romm above)

Thing 1:
The cogeneration possibilities mentioned by Joe Romm are a way to make the cost of electricity generated by by burning natural gas much closer to the cost of electricity generated by burning coal.

And natural gas can much more easily be distributed to locations where heat can be put to good use. In fact, it already is distributed to a sizable number of US households. Try that MR.Coal.

Thing 2:
Then we need a cogeneration power plant sized to fit the typical household. This has not yet been seen as a viable application by Solar Turbines of Caterpillar (last I checked) But it looks like it would be a lot easier to develop such equipment than it would be to squeeze CO2 out of the air. And CO2 capture? I remain skeptical when I see the size and rate of flow out of the power plant smokestacks. But maybe, ok.

Thing 3:
There is a real possibility that such a development is within reach using engines on automobiles that are tied to electric generators. Example:Prius. Well, not too good an example since this would be oversized for heat usage of most households. Maybe time bursts of operation would work.

Thing 4:
We already understand the physics subject of aerodynamics sufficiently to know how to greatly reduce energy required to push cars down the road at high speeds. Prandtl and Fuhrman figured out how to make airships with very low drag a hundred years ago. Perish the thought, they might have been engineers rather than physicists, though I don’t think they cared about this too much. Anyway, there are old fluid dynamics texts that show the ideal airship having a drag coefficient of about .06, which is about a fourth that of the best cars we now build. If you can talk people into riding with their rarely present companion behind them, it is possible to make cars half as wide. “Wait a minute,” you might say. “This means that a car could use 1/8 the energy pushing air.” You might even go on to say, “So the engines could be a lot smaller, maybe about an eighth the size of the engine in the Prius.”

Thing 5:
So why not make this new kind of car using hybrid methodology? Now you cut the energy needed for personal tranportation by a lot (not quite down to an eighth due to rolling resistance and such), compared to a Prius, and a whole lot more compared to a Hummer. And all people have to do is learn to ride in tandem. (And ride in a wierd looking car.)

Thing 6:
Oops, the car I talked about in thing 5 has a very small engine already tied to a generator. Now it fits with the heat requirements of many households, and by hooking up to the existing natural gas plumbing when parked, and connecting coolant and exhaust systems to the household, we can get the cogeneration that Joe Romm suggested. Now, it is on a massive scale.

Thing…:
The capital cost of this is next to nothing, or less. Wouldn’t the fuel cost savings when driving the car and the electricity cost savings when the car is parked make this into a formula that could greatly reduce CO2?

David B. Benson:

March 30th, 2008 at 12:46 PM

As but a discussion item, I point a method of capturing the carbon which surely works and is safe:

Ending Global Warming by Burying Biocoal
———————————————

Hansen et al., March 2008,”Target CO2: Where Should Humanity
Aim?” found here:

states that we need to soon reduce atmospheric CO2 from the
current 385 ppm to an initially desired 350 ppm for compelling
reasons. Here is a sketch of a plan for doing so.

The world economy is about 67 trillion dollars (GDP) per year.
Imposing a VAT of 1% raises 670 billion dollars per year.
This sum is used to grow biomass, convert it to biocoal, and
sequester the biocoal in carbon landfills, every year until
the goal of 350 ppm is met.

Using Powder River Basin style earth movement, it would cost
about $16.50 per tonne to sequester the biocoal. In addition,
the biomass must be harvested, moved to the hydrothermal
carbonization facility, converted to biocoal (while generating
some process heat for electricity generation), and then the
biocoal moved to the landfill site. I assume these steps can
be done, averaging over time and location, for only $33.50 per
tonne, under half the currently required amount in the so-
called developed world. So the carbon capture and
sequestration net costs are assumed to be $50 per tonne of
biocoal.

I will assume, for simplicity, that the biocoal is 85% carbon.
Humans are currently adding about 8.5 gigatonnes of carbon
(GtC) to the active carbon cycle per year, mostly by burning
fossil carbon. Just to maintain the current 385 ppm of
atmospheric CO2 then requires producing and sequestering
10 gigatonnes of biocoal per year. This costs $500 billion
per year, leaving a net of $170 billion available for
producing and sequestering additional biocoal to reduce the
concentration of CO2 in the atmosphere.

To reduce the concentration to 350 ppm requires removing
about 185 GtC from the active carbon cycle. At the rate
of an additional 3.4 gigatonnes of biocoal per year, using
the net funds available, we would remove 2.89 GtC from the
active carbon cycle each year. Assuming this is done at
a steady rate, it will require 64 years to bring about the
initially desired atmospheric CO2 concentration of 350 ppm.

March 30th, 2008 at 12:48 PM

It seems to me that pulverizing silicate minerals and strewing them in out-of-the-way places is a way of reducing net CO2 emissions that has already demonstrated itself and will be innocuous if scaled up enough that those net emissions are negative.

The CO2 will come to the strewn grains. Once they have become SiO2 and MgCO3 they can lie where they are. Transport issues therefore don’t seem to arise.

Martin Vermeer:

March 30th, 2008 at 1:24 PM

Re #7 James Annan: another situation where this technology might become attractive is when we overshoot and realize too late that we need to get atmospheric CO2 back down in order to prevent bad things happening. I see that’s Joe Romm’s argument as well (#11).

Also, imagine the situation where some (large) country just refuses to bring its emissions down, perhaps arguing that if the West did it, then they have the right to do it too. Still, in that case bribing and bullying in various mixing ratios are things to try first.

Jim Galasyn:

March 30th, 2008 at 1:26 PM

I’ve been following Klaus Lackner’s efforts in this area for a few years. Thoughts?

Global Research Technologies, LLC (GRT), a technology research and development company, and Klaus Lackner from Columbia University have achieved the successful demonstration of a bold new technology to capture carbon from the air. The “air extraction” prototype has successfully demonstrated that indeed carbon dioxide (CO2) can be captured from the atmosphere. This is GRT’s first step toward a commercially viable air capture device.

…

The carbon capture technology was developed by GRT and Klaus S. Lackner, a professor at Columbia University’s Earth Institute and the School of Engineering and Applied Sciences. The Tucson-based technology company began development of the device in 2004 and has recently successfully demonstrated its efficacy. The air extraction device, in which sorbents capture carbon dioxide molecules from free-flowing air and release those molecules as a pure stream of carbon dioxide for sequestration, has met a wide range of performance standards in the GRT research facility.

“This is an exciting step toward making carbon capture and sequestration a viable technology,” said Lackner. “I have long believed science and industry have the technological capability to design systems that will capture greenhouse gases and allow us to transition to energies of the future over the long term.”

The GRT’s demonstration could have far-reaching consequences for the battle to reduce greenhouse gas levels. Unlike other techniques, such as carbon capture and storage from power plants, air extraction would allow reductions to take place irrespective of where carbon emissions occur, enabling active management of global atmospheric carbon dioxide levels. The technology shows, for the first time, that carbon dioxide emissions from vehicles on the streets of Bangkok could be removed from the atmosphere by devices located in Iceland. This could present a solution to three problems that until now have posed intractable obstacles for advocates of greenhouse gas reduction: how to deal with the millions of vehicles that together represent over 20 percent of global CO2 emissions, how to manage the emissions from existing infrastructure, and how to connect the sources of carbon to the sites of carbon disposal.

“This significant achievement holds incredible promise in the fight against climate change,” said Jeffrey D. Sachs, director of The Earth Institute, “and thanks to the ingenuity of GRT and Klaus Lackner, the world may, sooner rather than later, have an important tool in this fight.”

A device with an opening of one square meter can extract about 10 tons of carbon dioxide from the atmosphere each year. If a single device were to measure 10 meters by 10 meters it could extract 1,000 tons each year. On this scale, one million devices would be required to remove one billion tons of carbon dioxide from the atmosphere. According to the U.K. Treasury’s Stern Review on climate change, the world will need to reduce carbon emissions by 11 billion tons by 2025 in order to maintain a concentration of carbon dioxide at twice pre-industrial levels.

…

Steve Albers:

March 30th, 2008 at 1:56 PM

I would give consideration to “biochar” or “terra preta”. This would be a somewhat more natural way to capture CO2 using pyrolysis of agricultural waste and sequestering the resulting carbon in the soil. This improves the fertility of the soil at the same time. It actually can make biofuels carbon negative if this is done right.

Here are two “must read” links to help understand the enormous potential here:

John Mashey:

March 30th, 2008 at 1:57 PM

R&D portfolio management, as learned at a place that was OK at this, Bell Labs (in its height in the 1970s):

1) Fund a lot of little R efforts, including relatively crazy stuff, like research on weird things on transistors in the 1940s. Modest $, spread around many research efforts, most of which won’t get far.

2) Pick a few of the more promising ones and do further R. Modest $, but bigger per project.

3) Pick a few of those for some actual development D. $$

4) Then see if you have some solutions that can be scaled up, which usually means trying them out in fair-sized installations. big D $$$

5) Deploy $$$$$$$$ which means, don’t do it until you know what you’re doing.

All of this often takes decades.

The most expensive things are to try to jump from an idea to 5) directly; this is usually a good way to waste a lot of money.

The problem of course, is that Bell Labs, in the days, could afford to do this, because AT&T had very long-term thinking for an industrial corporation. People actually worried about building things like “no more than 2 hours down-time in 40 years”, because some infrastructure actually lasted that long. Monopoly money helped :-) People (at Murray Hill especially) were often working on research that *might* lead to something in 20 years. On the other hand, most of us were building things for the next 1-5 years, with technology more-or-less in-hand, not waiting for the wonders that might happen in 20 years.

Venture Capitalists do not fund steps 1 & 2, at least not on purpose.

At this point, most real R pretty much has to be funded by government, which means it needs a coherent long-term plan for how to manage such, not in evidence of late. Some big companies do some funding of this, often via university programs, like Stanford’s GCEP, and that’s an encouraging trend, i.e., bulkier, longer-term funding for multidisciplinary teams.

Anyway, as Joe knows, good long-term R&D portfolio management is really needed, both to encourage the right sorts of research, encourage rapid deployment of existing technology, and discourage premature leaps into deployment.

Edward:

March 30th, 2008 at 2:32 PM

In the same way that lap-top computers use less energy than the mainframe prototypes of several decades ago the only result was a huge proliferation of electronic devices from the cell phone to the I-Pod. Necessitating things like the California Electronic Waste Recycling Act. If hydrogen fuel-cell cars ever becomes widespread the only result will be a huge depletion of more non-renewable resources as industry promotes “non-polluting” cars. A hydrogen nuclear reactor which would also have to be used to power the factories building these cars has a reaction temperature of 3 billion degrees. The hydrogen bomb is more powerful than a conventional nuclear fission bomb. There is no known substance that can withstand such sustained temperatures, so the reactors would have to be continually disassembled and buried at a toxic waste sight somewhere, probably where millions of people live. Then new reactors would have to be built consuming more non-renewable resources. Many of the mineral properties needed would be of an exotic nature and scarce so hydrogen reactors can only exist as long as these rare metals remain. They will be used up very quickly for the reasons given above. I’m not a geo-engineer but it doesn’t make much sense to destroy the world in the name of stopping green house gas emmissons.

March 30th, 2008 at 2:39 PM

CO2 sequestration in massive quantities may be the ONLY salvation for mankind. Everything else that we are doing or thinking of doing is trivial compared to the anticipated global population increase from 6.7 billion at present to 9 or 10 billion by 2050-2070. And every one of those 9 or 10 billion want water, food, warmth, transport and social contacts just like the “West” enjoys right now.
That’s 40% more consumers of energy in the next 40 years. How do we deal with that except by CO2 (and CH4) sequestration? Birth control for 3 billion women?
We have to accept that Nature will do the job for us. Drought, famine, disease and resource wars – starting soon in the fight for oil.

March 30th, 2008 at 4:25 PM

Efficient and economical air capture seems to be highly improbable from a thermodynamic perspective. Think of it this way, “air capture” is occurring on a massive scale all over the planet via photosynthesis, or natural carbon fixation. Can we possibly invent a process that can compete with natural photosynthesis which uses “free energy” from the sun and produces things of value such as food and fiber? Any artificial capture system will require energy investment (which costs money) and produce a carbon stream that needs to be disposed of (another cost).

Let continue to research this area, but lets not put too much hope in a thermodynamic sink hole. Instead, let’s nurture and restore the biosphere to do what it does best, fix carbon.

per:

March 30th, 2008 at 5:09 PM

Once had this idea that windmills could be used to counter the effect of soot and acidic sulfur haze downwind of coal power plants. The idea was simply to use the wings of the windturbine to spray a dilute magnesium carbonate/bicarbone solution into the air.( just like the wings of agricultural spray planes does)

Assume that the alkaline solution have to be dilute, 0.5 – 1 %, to make most of the magnesium carbonate small enough to get airborne and prevent unwanted fallout close to the windmill. In an CO2 capture project the opposite might be true, less dilute solution and big droplets in order to prevent a big reflective cloud downwind of the CO2 wash out windmill plant.

11. Joe Romm: Thermodynamics prohibits converting most of that waste heat into electricity. It is waste heat because it couldn’t be converted. It can only be used to heat houses in the winter.

0. Frank Zeman: Taking CO2 back out of the air has to require more energy that you got by putting the CO2 into the air in the first place. Basic thermodynamics says so. Using sodium or potassium to take CO2 out of the air seems to me like a good idea for terraforming Venus, if you find an enormous supply of reduced sodium or potassium in the Oort cloud. If you do it on earth, it is bound to require a self-defeating quantity of energy. May I suggest joining Lifeboat [http://lifeboat.com] instead? We scientists move to Mars, allow the coal burning part of humanity to extinct itself, and repopulate earth in a few thousand years. We need to get more women into science.

March 30th, 2008 at 7:35 PM

I wonder where we’re going to store all this CO2 once we’ve captured it.

CO2 at room temperature and normal atmospheric pressure has a density of 1.98g/lt. 1 tonne (a million grams) of it will take 1,000,000/1.9 = 526,315lt of volume, which is 526.315 cubic metres. A million tonnes will take up 526.315 million cubic metres, which is 0.526315 cubic kilomtres. A billion tonnes – which is half the mass of CO2 put out by US coal-fired electricity generation annually – will take up 526km3.

According to the most recent IPCC report, the world in 2004 produced 49Gt CO2-equivalent, of which 56.6% or 27.7Gt were CO2 from the combustion of fossil fuels.

Thus, to absorb all our CO2 from fossil fuel combustion would require 14,597km3 of volume annually, and we would of course still be left with 22.3Gt CO2e annually from other sources, more than enough to take us past 450ppm by 2100.

But let us not ask so much from CCS, asking it to absorb only 1% of all CO2 from emissions; we must still find 146km3 annually. Let’s imagine that we remove all 1,300Gbbl or so of oil and put the CO2 in its place. The oil gives us 207km3, enough for a year and a bit.

Of course we might also compress the carbon dioxide, down to liquid form at 60 atmospheres or so. This will then require only 243km3 for all the combustion of our fossil fuels, or a mere 2.4km3 for 1% of it. Of course, keeping CO2 liquid is far from a simple task, and preventing these billions of tonnes from leaking out seems difficult.

Again, I wonder where this great volume is to be found. Perhaps HG Wells’ molochs could be summoned to excavate the vast caverns required.

It’s a crock. Burn less stuff.

Phil Scadden:

March 30th, 2008 at 8:45 PM

Recent comments – in line responses has been blank again for a week. Its so much easier to read this when this has been fixed.

[Response: Agreed, but I’ve had to take it down for performance reasons – when I get a chance I will install a new plugin that doesn’t cause such problems. – gavin]

Stephen Gloor:

March 30th, 2008 at 8:45 PM

Or you could use it to make methane from hydrogen in a Solar Tower. This could keep the co-gen plants going for a while. While this does not make the CO2 go away it at least takes back out what is released.

March 30th, 2008 at 8:55 PM

Re 11 Edward Greisch

The payoff of heating houses with waste heat is that the natural gas that would otherwise be used is no longer required. Ideally, this could mean an system efficiency of 100% instead of the 34% thermal efficiency of the present US power grid fossil fuel plants. This alone is a lot.

I have looked at this quite a lot. Hot water is also needed. Clothes dryers use a lot of heat. But much more interesting is the possibility of using absorption chiller technology for air conditioners and refrigerators. This comes in various efficiencies, the better ones being more expensive. But the gas burning refrigerator was used in the US for many years, and industrial airconditioners use this technology.

In the scheme I discussed, there would be a car parked next to a household when an adult was present to need the air conditioning. Not always of course, but enough to make this an important large scale possibility, even in hot climates.

Re 26 Kiashu
I am also a little underwhelmed by the air scrubbing potential for real gains. We are going to pump the entire world’s atmosphere through this machine? Or would it be half of it to cut the CO2 count in half?

Gene Hawkridge:

March 30th, 2008 at 9:47 PM

Rising sea level and warming sea water will result in an increase in organisms that convert CO2 and various other minerals into carbonates. Carbonates represent a stable way to store carbon – no industrial process required. However, how much mitigation will this provide in a world where governments are already trying to figure out how to build more dikes to keep out the sea? I don’t expect that carbonate-producing organisms, alone, are a solution, but what can we do to encourage this natural carbon sequestration process, instead of squandering the opportunity in a futile attempt to hold back the rising seas?

March 30th, 2008 at 9:54 PM

20. Edward: There is no such thing as nuclear waste. It is fuel that needs to be recycled. Where in the world did you get a 3 billion degree temperature in the core of a reactor? “Hydrogen reactor” has nothing whatsoever to do with hydrogen bombs, and neither do fusion reactors. Nuclear reactors likewise have nothing to do with fission bombs. What was meant by “Hydrogen reactor”, I think, is an ordinary fission reactor used to generate electricity with which to electrolyze water, making H2 and O2.

We don’t recycle nuclear fuel because spent fuel is valuable and people steal it. The place it went that it wasn’t supposed to go to is Israel. This happened in a small town near Pittsburgh, PA circa 1970. A company called Numec was in the business of reprocessing nuclear fuel. I almost took a job there, designing a nuclear battery for a heart pacemaker. [A nuclear battery would have the advantage of lasting many times as long as any other battery, eliminating many surgeries to replace batteries.] Numec did NOT have a reactor. Numec “lost” half a ton of enriched uranium. It wound up in Israel. The Israelis have fueled both their nuclear power plants and their nuclear weapons by stealing nuclear “waste.” It could work for any other country, such as Iran or the United States. It is only when you don’t have access to nuclear “waste” that you have to do the difficult process of enriching uranium, unless you have a Canadian “Candu” reactor that runs on unenriched uranium.
Numec is no longer in business. The reprocessing of nuclear fuel in the US stopped. That was the only politically possible solution at that time, given that private corporations did the reprocessing. My solution would be to reprocess the fuel at a Government Owned Government Operated [GOGO] facility. At a GOGO plant, bureaucracy and the multiplicity of ethnicity and religion would disable the transportation of uranium to Israel or to any unauthorized place. Nothing heavier than a secret would get out.
Nobody is paying me to post this.

March 30th, 2008 at 10:23 PM

I have to agree with Kaishu (#26) that the problem is not capturing the CO2 per se but doing something with it. The annual respiration of the planet is still four or five times larger than the annual increase in CO2. Plenty of CO2 is captured and even transformed into a solid form, it just doesn’t stay captured.

The biochar suggestions look scalable, and we may even get into a competition about who gets the last bits of carbon for soil improvement as we approach 300 ppm. But, it is not yet clear that biochar remains as stable as coal in the ground in all soil ecologies so a portion of our sequestration activities should also be aimed at reconnecting carbon to the geological cycle through formation of calcium carbonate. It seems to me that protecting existing reefs, establishing new ones where they will flourish in a changing water temperature environment, and generally promoting healthy estuaries where mollusks can reestablish their historic abundance should be major priorities. Biochar may have a role in buffering nitrogen to help with this.

So far as I can tell, the only place where we actually need liquid hydrocarbon fuels is in aviation. My estimate of how it might be produced competitively using air capture of CO2 is here. Christopher Graves, a student of Lackner’s, feels that a larger scale system that still makes use of the process heat might make a better first start and there are a number of existing university co-generation plants where a heat distribution system is already in place that might make good demonstration project sites. During the period of time when natural gas generators are still in use, it may make sense to use the Sabatier reaction in cogeneration plants to produce methane when the wind blows and then use the the methane in the turbine when the wind does not blow. Because the heat from the electrolysis of water and the formation of methane can be used just as the waste heat from the turbine is used, the conversion of wind power into methane is essentially one-to-one. Again, air capture of the CO2 feedstock can make sense if there is no nitrogen free source nearby. Of course, the turbine, when it is used, might be fed the coproduced oxygen from the electrolyis so that the turbine exhuast is nitrogen free, making a nice closed system.

I think that air capture is good for making fuel, and much more efficient than attempting to make fuel using plants, but storing carbon as CO2 seems like an endeavour fraught with perils whereas storing (nearly) elemental carbon or mineral carbonates is just how the Earth manages carbon balance. Coal left in the ground is the best form of sequestration there is. It is here, rather than in making fuel, that biological assistance can be most fruitful. Reforestation, rebuilding soils with biochar and reviving the oceans, because they turn carbon into a solid, are the way forward for sequestration rather than foolhardy attempts to contain a water soluble gas.

March 31st, 2008 at 12:44 AM

We should not ignore NO2 levels.

“It only makes up 9% of total greenhouse gas emissions, but it’s got 300 times more global warming potential than carbon dioxide”, says Prof Richardson. “It can survive in the atmosphere for 150 years, and it’s recognised in the Kyoto protocol as one of the key gases we need to limit”.

March 31st, 2008 at 12:59 AM

Re: Kiashu #26,

The IPCC estimate from the Special Report on Carbon Capture and Storage is that the geological formations (principally deep saline aquifers) can store 2000 to 10000 GtCO2, which is of course much, much larger than the ~30 GtCO2 emitted per year.

You are right that the volume numbers are large, but the Earth’s surface is enormous (~150 million km^2 of land). Depths upto 3 km are easily accessible, and even deeper areas are reachable but probably less interesting. You only need a small fraction of that to be able to accept CO2 at 70-100 bar to come up with a large hypothetical storage area.

Most CO2 injection would be into pore spaces in sedimentary formations currently occupied with water. You don’t need “caves”, merely porous rocks, which are relatively abundant in sedimentary formations. (Also the fraction of rocks that qualify as porous improves considerably when you drive CO2 in at an overpressure of 100 bar.)

There are plenty of technical challenges with CCS, but most analysts currently think there is more than enough capacity for the needs during this century.

March 31st, 2008 at 1:03 AM

I was inspired to research is a little bit and write an article on it. To be honest it’s really unpromising – in their remarkably few tests it’s leaked out.

Jerry Toman:

March 31st, 2008 at 1:50 AM

I’ve commented on ideas similar to this before and I am surprised they keep coming up time and time again as if none of us here has never had a College P. Chem. or Chemical Engineering course emphasizing thermodynamics as the basis for chemical equilibrium.

J. Willard Gibbs, one of the most revered icons of American Science, spent a lifetime of careful analysis to establish the validity of the “new” science of Thermodynamics. His purpose was to provide the tools to make sure ideas like this would be nipped in the bud before they gained too much “political traction”.

One of the main tenents of the science is the Second Law which states that in every process that occurs at a finite rate, there are irreversibilities, which result in increases in entropy.

Far less entropy is created if CO2 is captured directly from flue gas at concentrations of up to 100,000 ppm, than if it is first allowed to mix irreversibly with air, diluting its concentration down to 400 ppm.

As a practical example from the discussions, it is suggested that CO2 be captured using strong bases such as sodium hydroxide or potassium carbonate. Of course we know this is possible as anyone who has left open a container containing these substances to the air has realized.

The problem is that the heat of reaction required to absorb the CO2 must be very high to overcome the high entropy of CO2 in air. This “heat of reaction” is dissipated and put to no good use. When the CO2 is regenerated, however, (if even possible) the heat must be put back in.

One the other hand, when treating flue gases containing much higher amounts of CO2, a much weaker base, such as a (promoted) monoethanolamine solution can be used to absorb the CO2. The CO2 is regerated from the solution at slightly above atmospheric pressure by applying heat (to a reboiler) at about 250 F. The system makes effective use of a “cross-exchanger” to transfer heat and minimize “irreversibilities”. This is one of the “preferred” ways the DOE is funding the clean coal initiative. Even this (plus compression of CO2) causes a loss of about a one-third of the electrical output from the plant.

Of course, because it is a relatively “weak base” MEA would be useless in absorbing CO2 directly from air.

The bottom line is that there is a dilution factor beyond which a point of economic “no-return” is surpassed for which it doesn’t make sense (e.g., low-grade uranium ore, uranium in sea water, low-grade iron ore, or in this case, CO2 in air), to expend energy to recover it. This is without even mentioning the embodied energy in the equipment used to carry out the process.

Suggestion: If we are getting off on a geo-engineering tangent, may I suggest you invite Louis M. Michaud of AVEtec to discuss some ideas on how a fleet of stationary vortices might be deployed in the atmospshere to cool an area, perhaps a very large one (Great Lakes region) and return it to its historical temperature levels, or to discuss any topic he may wish to address with regard to about how the Atmospheric Vortex Engine can be used to mitigate climate change.

At least he knows Thermo…

JeandeBegles:

March 31st, 2008 at 2:21 AM

I am very skeptic about the feasability of CO2 removal in the atmosphere; the natural mechanisms performing it (photosynthesis and sea absortion) work very slowly and are efficient because spread all over the earth. More, the CO2 concentration is rising, and this is a problem, but the number remains very low (0,04%).
So I would be very surprised if a real solution come out of this path.
What is a fact is that some of theses studies are founded (linked) to the oil industry. Then the purpose is more obvious. No need to care about our CO2 emission, no need to tax carbon or even cap and trade, there will be an easy way to remove this CO2 pollution!
So these studies about CO2 removal, that look like fancy thinking, may be more about global warming fight removal.

March 31st, 2008 at 2:26 AM

Interesting. I agree with Kiashu (#26). Where are you going to put it? Even if you can convert the CO_2 to a solid form chemically, you end up with at least as much volume as the original coal.

I don’t buy the concept of compressing the gas and storing it deep underground. Sooner or later if that is done often enough, a mistake will be made and it will force its way out somewhere unexpected. Examine the costing in CCS schemes of this sort of failure, and you see a big finger pointing at “government” (i.e., us) as the insurer of last resort because the cost of a catastrophic failure is so high.

Meanwhile, a little OT, but I thought some here may appreciate this (posted a day early to allow time to get through moderation):

Nigel Williams:

March 31st, 2008 at 3:25 AM

Kaishu – you’ve got it in one! Of course IF as from yesterday we sequester all we emit and the same again the problem will go away. Of course IF we stop demanding more energy we will stop building fossil-fuelled power generation and we will stop the rot. Of course IF we turn off all our lights, cook on solar stoves, bin our PCs, insulate our houses, beds and quilted jackets with straw, wool and down and we walk everywhere behind cart horses and beat our fast food fat fryers and TIG welders into ploughshares, then our energy needs will drop and things may be better.

But let’s get real folks. We wont. Someone somewhere is going to keep on doing the bad things for our planet, in fact everybody is going to keep on doing it until the lights go out at their place, or until their carpet is wet with salt water, or until they have nothing to drink and/or nothing to eat.

Because deep down it is our fervent hope that this is all a bad dream. That Mother Nature will kiss the Earth and make it all better. But this time we have run out of favours. Our nine lives are cut.

We know enough to foretell our end with out persisting with the endless examination of the minutiae of political, social or of climate science. We know there is enough climate change in the pipeline to pretty well end life as we know it – even if we turned off all the motors today. We know that as our present society expires it will go like the end of a small star; in a final stuttering surge of conspicuous, indeed of desperate consumption of the remaining resources. Emissions will peak, as a final gesture of our defiance at all-avenging Gia. From then on it will be all down hill.

The astute among us will try and make other arrangements; to adapt – as the technical optimists euphemistically put it – but even so I don’t like our; I dont like my chances.

March 31st, 2008 at 4:20 AM

Re #14 David B. Benson:

So the carbon capture and
sequestration net costs are assumed to be $50 per tonne of
biocoal.

…and there’s the rub. Politics. Once we get to spend $50 to keep a tonne of coal out of the atmosphere, there are lots of technologies that suddenly become interesting. And the portfolio approach of John Mashey #19 the only sensible way.

Re #20 Edward:

There is no known substance that can withstand such sustained temperatures, so the reactors would have to be continually disassembled and buried at a toxic waste sight somewhere, probably where millions of people live. Then new reactors would have to be built consuming more non-renewable resources.

I get the impression you are mixing up the “hydrogen economy” with nuclear fusion. But apart from that, the above is not true: there are two techniques for containing a hot fusion plasma, magnetic containment and inertial containment.

The problem isn’t heat but neutron activation: the fusion energy is carried off as fast neutrons, which can be captured in a lithium blanket for breeding new fuel. They will however also be absorbed in structural elements of the reactor, which thus will become radiactive and, after a while, structurally compromised. So yes, “used-up” reactors will have to be disposed of, just like with fission reactors. But the difference is that the process itself doesn’t produce any high active waste, just helium.

Re #25 Edward Greisch:

Taking CO2 back out of the air has to require more energy that you got by putting the CO2 into the air in the first place. Basic thermodynamics says so.

Yes, but only if you convert the CO2 back to C. Otherwise it is a lot less (but still much).

Re #26 Kiashu:

CO2 at room temperature and normal atmospheric pressure has a density of 1.98g/lt

Of course we might also compress the carbon dioxide, down to liquid form at 60 atmospheres or so. This will then require only 243km3 for all the combustion of our fossil fuels, or a mere 2.4km3 for 1% of it. Of course, keeping CO2 liquid is far from a simple task, and preventing these billions of tonnes from leaking out seems difficult.

The density of liquid CO2 is 1600 g/liter ( http://en.wikipedia.org/wiki/Carbon_dioxide for solid, but I expect liquid to be similar). So you would only need to store 18 km3, or 0.18 km3 for 1%. If you store this under a 100×100 km area, it would rise by 18 mm/year.

These same layers have safely contained oil and gas for millions of years. The oil industry is already using CO2 injection into wells for recovery of oil, and leakage doesn’t seem a major problem. And even if some leakage were to occur, remember current leakage is 100% :-)

Burn less stuff.

Agreed.

Johnno:

March 31st, 2008 at 5:47 AM

I suspect that when biochar is studied more carefully the effective carbon capture won’t be so great. So far most of the bio-carbon comes from outside the test farm field into which it is plowed; example forestry waste. However left alone it may (depending on humidity and fire) remain as near-inert carbon in forms such as bark, fallen trees, leaf litter and humus. By harvesting and partially burning that biomass we accelerate atmospheric CO2 addition. The difference is that we accurately measure that leftover charcoal in grams added per square of farm soil. In contrast we only guess at the unburnt yet semi-stable litter back in the forest, perhaps also downplaying the liquid fuel requirement for harvesting machinery. I think burn less carbon period whatever the source.

Jim Cripwell:

March 31st, 2008 at 5:59 AM

I find it interesting that no-one seems to have mentioned Craig Ventner (? spelling). If Craig is successful, his micro-organisms which “eat” CO2 and produce methane or other hydrocarbons, will require an atmosphere of almost pure CO2 to live in. These organisms may be only 18 months away. This is certainly as long as it will take to build carbon dioxide sequestration hardware.

Francois Marchand:

March 31st, 2008 at 6:17 AM

Re N° 40 – I thought that even the carbon sequestering enthusiasts had never imagined liquefying CO2, cooling it down a bit (say down to a couple dozen degrees K), and pumping it down in some old mine shaft, for it to stay there for an eternity (until we die, that is). The amount of energy needed… There are laws against that : thermodynamics.

pete best:

March 31st, 2008 at 6:32 AM

It is as had been stated already. The worlds energy comsumption is growing by 2 – 3 % per year. Therefore all new energy requirements/demands should be met with non fossil fuel technology wherever possible but that still leaves the existing infrastructure pumping out some 7+ billion tonnes of CO2 per annum which has to be dealt with.

Heating your home via is the most energy intensive practise even though it usually burns gas locally you get through a lot of KWh of it in a cold country. Here in the UK its around 20,000 KWh.

Electricity use is quite low, around 5000 KWh per average house. A UK (4.5 litres relative to the US 3.9) gallon of Petrol produces some 43 KWh of energy so the anount used depends on mileage done and fuel conumption per annum. The average in the UK is 9000 miles and 32 MPG. The average in the USA is 12000 miles are 20 MPG. Petrol produces some 2.3 Kg/Litres of fuel used whilst diesel 2.6 Kg/litre used. Diesels also produce black carbon recent articles have stated.

Therefore cost effictive measures to curb carbon use or increase efficiency range from lagging your loft and cavity wall insulation, double glazing, wearing a fleece and slippers in the winter – effective measures for staying warm to driving a more economic car (20 to 40 mpg makes a big difference tonnage wise) to using the new CF lightbulbs and AAA rated applicances (lowest gain). The average american produces some 6.5 EU tonnes of Co2 per annum. There is massive scope for efficiency gains here.

On solar power for example. A typical system here in the UK costs around £5K with the grant and will produce some 800 – 1200 KWh of electricity per annum (20 to 25%) saving but it will never pay for itself at the present time and solar is seasonal and hence a lot of it is sold back to the grid. Relative to overall energy usage solar is poor value for money compared to getting a new fuel efficient car (when you next buy a car) or insulating your home and wearing more clothes inside the house.

JCH:

March 31st, 2008 at 6:38 AM

” And maybe both of these advantages could be combined, eg via my patented maintenance-free floating rafts of coconut trees which directly sink their genetically-engineered carbon-heavy fruit to the ocean floor for long-term sequestration (you read it here first, folks). …” – James Annan

I’ve suggested this same thing. In Wisconsin they are salvaging massive old-growth logs that sank during logging operations done in the 19th Century. They’re still in excellent condition. It’s some of the most valuable timber on the market.

March 31st, 2008 at 8:14 AM

I see it as a possible transitional solution buying us time. Which we’d better use wisely.

Ray Ladbury:

March 31st, 2008 at 8:16 AM

There appears to be a lot of misinformation among posters about what is involved in carbon sequestration. It does not involve turning the CO2 into carbon, so you don’t give up all the energy you got from burning the carbon in the first place. Rather, it involves causing the CO2 to react or bind with a material and then either storing the reaction product or freeing the pure CO2 and storing it in liquid or solid form. CO2 liquifies under pressure, so this is not prohibitive energy-wise.
And yes, the normal processes that take up CO2 are slow, but it is quite possible they can be sped up via catalysis or using nanoparticles. So bottom line: There is nothing in the laws of thermodynamics that precludes carbon sequestration. Whether it can be made economically viable is entirely another question. The problem Frank is addressing here is especially problematic, since 1)CO2 emissions from a point source are concentrated, so much of the work is already done for you; 2)distributed sources preclude an efficient centralized plant; 3)No one has even shown that carbon capture and storage could be made to work even for a point source.
The non-point source problem seems to become more urgent as development progresses. Early in development, there is a migration to cities, as increased agricultural efficiency causes people to migrate there looking for work. Later on as people become more affluent, the migration is away from the cities, and distributed emissions increase. The problem is in some ways very similar to that of pollution of the watershed. Cities can solve their problems by improving sewage treatment, while emissions from suburbs are much more difficult to control.

Frank Zeman:

March 31st, 2008 at 9:01 AM

Wow! Really interesting comments for the most part. I was originally thinking of trying to respond to most of them but that seems like a full time job. Having scanned a few of them I thought I would make a few comments.

1) Air Capture is not expected to be cheaper or easier than capture from power plants. This technology is aimed at vehicles and other small sources of CO2. Recall the IPCC threshold for capture was 0.1 MtCO2 per year, which I think is a 100 MW coal plant (don’t remember exactly).

2) Air Capture is essentially a CO2 concentrator meaning the CO2 would have to be stored or converted back to fuel through CO2 hydrogenation. The latter idea is not as crazy as it sounds and the carbon essentially becomes a hydrogen storage device. The tradeoff is the cost of capturing and converting the CO2 to fuel versus transporting and storing H2 along with new re-fueling stations and vehicles.

3) The best estimates for the energy consumption of AIr Capture is 350 kJ/mol CO2. I think we can get that down to 250. The heat released from coal is 400 kJ/mol CO2 with all other fuels higher owing to the hydrogen present. While not super efficient, we regularly accept only 35% conversion of coal to electricity.

4) If the CO2 is to be stored the Air Capture allows capture at the storage site, thereby avoiding large transportation networks and opening isolated storage sites to operation.

Just some thoughts.
Frank

March 31st, 2008 at 11:06 AM

This is great!

I’m thinking we could do 2 things — stop emitting GHGs as much as possible (efficiency, conservation, EVs plugged into solar/wind power), then also suck out even more CO2 from the air than what we’re emitting through fossil fuel burning. That way we might be able to bring the ppm down to a better number. However, I guess it would also be taking out our current CO2 from respiration, etc, since much the previously emitted CO2 (that didn’t get absorbed soon after emission) is way high up in the atmosphere where such air-capture systems won’t work. Would the plants be OK with that?

John Lang:

March 31st, 2008 at 11:07 AM

This project has been/will sink 26 megatonnes of CO2 and enhance oil recovery by 155 million barrels. The project is being carefully studied as it rolls-out and several papers have been published in journals which prove the CO2 will be sequestered for thousands of years at least.

This is the kind of project which should be pursued first. The economics are so good for the oil company Encana that they are paying a rumoured $100 per tonne (7 times the current market rate) for the CO2 produced in a North Dakota coal gasification plant.

A new coal-fired power plant is planned nearby (construction to start this year) which will also capture the CO2 and, presumably, use a similar process in the oil fields in the area.

So, it can be done. People just need to keep the economics and cost in mind. In this case, a side-benefit of increased oil production more than pays for the cost of the project. Of course, the geology has to also be conducive to permanently storing the CO2.

March 31st, 2008 at 11:09 AM

1)CO2 emissions from a point source are concentrated, so much of the work is already done for you;

‘Vagueofgodalming’ mentioned exothermic weathering, and linked a Wikipedia page with varying content. Its assertion that olivine’s iron-free end member is forsterite, Mg2SiO4, sounded reasonable.

Although pulverized and strewn forsterite has not had the work of CO2 concentration done for it, the data say it is ready to do it. The work of concentration is about 20 kJ/(mol CO2), and forsterite’s reaction with CO2 yields 33 kJ/(mol CO2). (That is the minus-delta=’G’.)

So it is not surprising that, as he or the article said, pulverized olivine weathers quickly. But the reaction cannot generate thermal power; it would run out of minus-delta-‘G’ around 200 Celsius, and be very sluggish indeed some tens of K below that.

2)distributed sources preclude an efficient centralized plant;

No, they don’t, because CO2 can come to such a plant from the whole atmosphere.

3)No one has even shown that carbon capture and storage could be made to work

Serpentinite-containing mine tailings have in fact shown this, without the mine operators’ intending it. As above said, they took some CO2 from every puff that every tailpipe has puffed.

BRIAN M FLYNN:

March 31st, 2008 at 11:58 AM

Frank:
You say:
“However, the cost of air capture is still basically unknown.”
and, in comments:
“The tradeoff is the cost of capturing and converting the CO2 to fuel versus transporting and storing H2 along with new re-fueling stations and vehicles.”

I suggest you may want to view CO2 capture and conversion to sulfur free, carbon neutral synthetic gas production and organic chemicals(see e.g., Green Freedom™ at: http://www.lanl.gov/news/index.php/fuseaction/home.story/story_id/12554)
The design (for now) is to use existing nuclear power with existing nuclear plant cooling towers as the point of carbon capture thereby to keep infrastructure costs low. Proponents claim that the price at the pump for such gas (with allowance for profit) would have to be about $4.60 per gallon, but with certain technological improvements, the price could be reduced to $3.40 per gallon – where we are presently. It appears worth piloting now.

David B. Benson:

March 31st, 2008 at 12:33 PM

Biochar makes a most useful soil amendment. But about half of the carbon returns to the active carbon cycle with a few years. Moreover, the storage time of the remainder is unknown. The linked report summarizes current understandings regarding biochar:

Applying biochar to improve the soil is a great idea. But I don’t look to this as a long term solution for removing the excess CO2 from the air.

Jim Galasyn:

March 31st, 2008 at 12:58 PM

Rising sea level and warming sea water will result in an increase in organisms that convert CO2 and various other minerals into carbonates.

This is probably not the case for a high-CO2 world, because the oceans become more acidic; eventually calcareous creatures can’t make calcium carbonate and their numbers drop steeply. This effect has been clearly observed in ocean sediments from the PETM.

I don’t expect that carbonate-producing organisms, alone, are a solution, but what can we do to encourage this natural carbon sequestration process, instead of squandering the opportunity in a futile attempt to hold back the rising seas?

Jim Galasyn:

March 31st, 2008 at 1:09 PM

I’ve often wondering if it would be possible to separate CO2 electrostatically: suck air into a chamber and zap it with a laser that’s tuned to the right frequency to ionize only the CO2. My very primitive reference design is here. Obviously, such a unit should be solar powered.

There’s also been some very interesting work on smart membranes that allow only CO2 molecules to pass through them.

March 31st, 2008 at 1:11 PM

Frank,

#50. What pressure are you taking as the final pressure for your estimate of 350 kJ/mol? At 17 atmospheres final pressure I calculate that using a zeolite based system similar to what is used on the space station the energy requirement is about 34 kJ/mole. 17 atmospheres is a good pressure for Fischer-Tropsch. If you see an error here, I’d appreciate hearing about it.

Thanks,

Chris

Kevin Leahy:

March 31st, 2008 at 1:23 PM

Some of these perhaps represent new ideas. However, this topic has already received quite a lot of attention for some time.

Until or unless some breakthroughs occur, it looks as though the most economic (i.e., lowest costs) solution is to capture the CO2 off of an integrated coal gasification unit. The remaining hydrogen is then combusted in a combined cycle electric generating plant. Oxyfueled plants may also work, resulting in an exhaust stream that is almost pure CO2. The electricity can fuel your transport fleet (except aviation, which is used only for long distances). For this, we need better electric storage.

The CO2 off the IGCC is already at very high pressure, so you have less cost to compress it for the geologic storage. And in regard to the risk — we are talking about 1 to 2 miles underground. The risk is in a slow leak, not a catastrophic release. This is more of a financial issue for those undertaking the work (they avoid a cost under a cap and trade or carbon tax regime — if you leak, you pay). Oil people laugh when people say “if it works” as they refer back to the fact that the proper geology keeps natural gas underground just fine.

Finally, to remove CO2 from the atmosphere, if it comes to that, the current thinking is that it may be more cost effective to harvest biomass and run it through above gasifier, with the CO2 stripped out and geologically stored. A twist on this theme, some are talking about using algae as the biomass source. Others are considering the economics of growing it in an enriched CO2 environment as found in the flue gas of a conventional power plant, then gasify and store underground.

Phil. Felton:

March 31st, 2008 at 1:44 PM

Re #33We should not ignore NO2 levels.

Indeed we shouldn’t, however what is being referred to is N2O!

March 31st, 2008 at 2:10 PM

In regard to operating carbon sequestration systems, there is project in the weyburn, saskatchewan oil field, installed around 2000, which takes CO-2 piped from a North Dakota coal gasification plant, and forces the CO-2 into the oil field area, (thereby enabling recovery of more oil). Google: CO-2 sequestration + weyburn saskatchewan. This installation appears to operating successfully, giving us some hope in this method of CO-2 storage.

Adrian:

March 31st, 2008 at 2:23 PM

Hey thanks for the great blog, I love this stuff. I don’t usually do much for Earth Day but with everyone going green these days, I thought I’d try to do my part.

I am trying to find easy, simple things I can do to help stop global warming (I don’t plan on buying a hybrid). Has anyone seen that http://www.EarthLab.com is promoting their Earth Day (month) challenge, with the goal to get 1 million people to take their carbon footprint test in April? I took the test, it was easy and only took me about 2 minutes and I am planning on lowering my score with some of their tips.

I am looking for more easy fun stuff to do. If you know of any other sites worth my time let me know.

JCH:

March 31st, 2008 at 2:30 PM

One of the papers I read says CO2 stored at depth essentially cycles out of the ocean in 900 years. Is that correct? Has anybody considered “containerizing” liquid CO2/dry ice at the bottom of the ocean.

Rod B:

March 31st, 2008 at 3:05 PM

I’m a little behind (aren’t all us skeptics??), but am I alone in thinking TEQS scheme is a pie-in-the-sky pipedream (to double up my metaphors). From a practical view? Instead of starting with some technology base, it seems we just allocate carbon usage to people, reduce those allocations each year, and just let the poor saps figure it out.

C L:

March 31st, 2008 at 3:36 PM

Can anyone tell me whether thorium based nuclear energy, as suggested in this article, is a credible alternative to conventional nuclear power, please ?

March 31st, 2008 at 3:38 PM

# 30. Gene: The present rate of sea level rise is probably good for encouraging reef growth since the reefs like to maintain a certain depth to have adequate sunlight. A rising sea level gives them room for growth. However, current land use practices discourage reef and mollusk growth because silt fouls the water and nitrogen runoff encourages so much algae growth that the decay of that material creates anoxic conditions which destroy aquatic ecosystems. Corals also seem to be sensitive to the increase in water temperature and will eventually run into trouble owing to ocean acidification. The rate of sea level rise we might expect towards the end of the century, a centimeter per year or so, will be too fast for coral growth to maintain depth so there is a balance. Now would be the time to take advantage of a favorable sea level rise rate. To do this we would need to sharply reduce soil erosion and nitrogen runoff. There are a number of agricultural practices that can help with this and one of the most exciting is the way that biochar can hold nitrogen and help to keep it in the soil and out of the water, though conventional organic methods of agriculture are already available to help. http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1091304

In terms of issues with water temperature changes reducing reef growth, the establishment of new reef in a manner that anticipates expected changes might make sense. Also, introducing warmer water corals to reefs that are warming may help. To get a lot of sequestration from reefs we would need to increase their surface area in any case. I make some estimates here. Increasing the current surface area of coral by a factor of 15 appears to sequester all of our lingering emissions to date.

Ike Solem:

March 31st, 2008 at 4:04 PM

We’ll never be able to halt the continuing increase in atmospheric CO2 unless we stop using fossil fuels. If we did come up with an energy source sufficient to capture and stabilize all the CO2 emitted by the burning of fossil fuels, we wouldn’t need fossil fuels at all.

The notion that one can burn coal, capture the CO2 and store the CO2 in a stable form approaches a perpetual motion machine strategy. Estimates vary, but to capture all the carbon coming out of a coal-fired power plant would require a minimum of 30% of the energy generated, likely much higher. When a solar PV system or wind turbine operates, in contrast, no emissions are generated at all.

The multibillion DOE dollar project which was supposed to demonstrate coal sequestration was dubbed “FutureGen” and has been abandoned, despite all the hoopla. It proved to be incredibly expensive as well as ineffective, and found no investors.

There are alternatives, however – the conversion of photosynthetic biomass to charcoal and burial in the soil apparently results in storage of about 20% of the original carbon in the biomass, and produced biofuels as well. However, there’s no way to get around the need to halt the use of fossil fuels, starting with coal.

March 31st, 2008 at 4:19 PM

From what we see happening now, sea level rise towards the end of the century will
be substantially faster than “a centimeter per year or so”, and will come in spurts.

Daniel Nall:

March 31st, 2008 at 5:26 PM

As an energy conservation engineer, my hopes for widespread implementation of this technology are very dim. It is highly capital intensive and its only product is carbon mitigation. A more likely carbon sequestration technology is the pyrolysis of organic and agricultural waste to produce gas that can be burned for electric energy and substantial amounts of carbon char that can be mixed with soil as a component of fertilizer. The process produces somewhat more energy than is required for the heat of pyrolysis, so that additional saleable products, power and powdered carbon are produced in addition to carbon credits.

I think the best hope for large scale carbon reduction is to convert as much energy-consuming activity as possible to electricity and concentrate on low carbon power production. If a reasonably power dense electric storage medium could be found, this strategy could even be applied to mobile energy users such as vehicles. In this scenario, hydrogen can be viewed as a transport and storage medium to be evaluated according to its efficacy in those functions. As someone has said, ” the only problems with the hydrogen economy are that hydrogen is difficult to transport, difficult to store and we don’t have any of it.”

DBrown:

March 31st, 2008 at 5:29 PM

This is a joke? No person with any knowledge of statistical thermo really thinks that we can remove such a tiny trace gas (CO2) from our vast atmosphere insuch a way that any real measurable impact on the atmosphere would be achieved?
Lets look at a few minor numbers: Volume of main atmoshere:1,071,821 km3 (for about 20 km thick sphere over Earth surface (really more but lets use a minor number.) Assume we have a truly amazing processing system: 1 km3 total volume (over ‘n’ process plants) that can operate at the rate of 1 km3 per day is completely done; CO2 is 0.038%; so, lets assume we will remove ‘half’), then 535,910 km3 would need to be processed to get this value.
then in only 8,213 years, the first run would be complete (this fails to take into account that the released air mixes with the current untreated air which would vastly lengthen the required time).
This idea is so ridiculous that I cannot understand why anyone would discuss this absurdity in this column. This undermines a very good and serious site.

Jim Galasyn:

March 31st, 2008 at 5:52 PM

Re JCH’s question in 63 about carbon sequestration at the ocean floor:

I saw Tim Flannery speak a couple of years ago, and he mentioned that experiments had been done along these lines, but the effect on marine life was disastrous. Asphyxiating deep-ocean corals and associated ecosystems with billions of tons of liquid CO2 would be a treatment that’s as bad as the disease.

March 31st, 2008 at 6:30 PM

C L #65: Thorium sounds great compared with uranium. I suspect it was not developed because the precursor industries were already there for weapons production, favouring uranium. Also, the fuel production process is complex. I remain sceptical of anything that looks good as a bunch of equations and pilot studies until it has been worked through to a production-scale plant. Even if all the claims pan out, if will be decades before thorium-based power could make a significant difference. In short, even if it is a good idea, it will not be possible to scale up fast enough to make the sort of difference we need.

Some good comments on the Cosmos web site where you found the article.

In the looks too good to be true department, has anyone seen this? http://focusfusion.org/ — claims to have a new fusion process which doesn’t require radioactive inputs, doesn’t create radioactive outputs, and can be used to generate electricity directly without the usual lossy heat to steam to rotation to electricity steps.

March 31st, 2008 at 6:56 PM

Re 70

Though my interest in geoengineering lies elsewhere,the joke may be on DBrown, in reckoning a throughput much higher than a cubic kilometer of air a day “so ridiculous that I cannot understand why anyone would discuss this absurdity in this column.”

As 1 Km3 weighs roughly 10 exp 9 kg, processing such a volume works out to ~ 150 grams of air per capita, per diem.

Since we breathe roughly an order of magnitude more than that, processing a far larger mass of air seems within the bounds of energetic and economic possibility.

March 31st, 2008 at 7:57 PM

65 CL: Yes, Thorium can be “bred” into uranium 233 by putting it into a reactor. This is just like making plutonium from uranium 238. Uranium 233 is fissionable just like U235. Since there is more that twice as much thorium as uranium in the world, breeding thorium into U233 multiplies the available nuclear fuel by several hundred times. Likewise for breeding plutonium from U238 and using plutonium as reactor fuel. Since only 0.7% of uranium is U235, the rest of the uranium is wasted unless breeding and reprocessing are allowed. Thorium as a source of fissionable uranium is indeed an excellent idea. The problem is paranoid people. I don’t know why so many people are irrationally fearful of all things nuclear, but I think that coal company propaganda has something to do with it. By the way, coal contains so much uranium and thorium that more energy by hundreds of times goes up the smokestack and into the cinders than you get by burning coal. Nuclear power is far safer than coal power.

Could somebody write down the chemical equations for how CO2 becomes stuck in coal and other things, please. Are these processes reversible? How much do we have to worry about asphyxiating because of a CO2 leak if we live near a sequestration site of type X? CO2 from Lake Nyos killed 1,700 people. How much of this is driven by the coal mine lobby? 100%?

Would you really want to make CO2 back into a hydrocarbon fuel, or would it be easier to convert a car engine to run on ammonia? Hydrazine is out because hydrazine is a monopropellant/explosive. There must be more economical ways to propel cars than making hydrocarbon fuels out of CO2. What about batteries, perhaps with overhead wires to do quick recharges while driving? Airplanes can use hydrogen because large tanks or cryogenic tanks would be less of a problem for aircraft. Trains can use third rail electricity.

70 DBrown: Thank you. I agree that taking CO2 out of the air by an industrial machine strikes me as preposterous. And making CO2 back into fuel seems equally preposterous. If we had an infinite supply of free energy, we could do it; but it would be done with tax money and therefore cut from the budget before it got into the budget. There must be easier ways to do what needs to be done if we can overcome the fossil fuel lobby in Washington. Coal alone is a $100 Billion industry in the US alone.

29 Jim Bullis: How much does all the plumbing cost? How do you get people who live near the source of waste heat to go for all of that stuff? It would work if the place that generates the waste heat is also the place that uses it. It also worked in the old Soviet Union where the town was built to tend the breeder reactor. There is less central planning here, and maybe you need central planning to make waste heat useful much of the time. Sometimes it works.

GlenFergus:

March 31st, 2008 at 8:36 PM

OT: Whereto HadCRUT/NCDC/GISS?

Time may be fast approaching when we need another post from you guys on the various global temperature series. All that sound and fury of the “warming stopped in ’98” crowd could rate as something-nothing if the current blip persists awhile. Monthly HadCRUT is now back to 94-96 levels.

Presumably the Pacific just burped some cold stuff. ENSO, sure, but might something else be happening? What would an IPO/PDO phase shift do? That one was mostly warm through ’46, cool through ’76, then warm again since – an occasionally discussed correlation. What if we’re building another temperature saw tooth?

Robert:

March 31st, 2008 at 8:36 PM

As a chemical engineer, I must agree with previous comments that air capture of CO2 is impractical compared to other carbon capture alternatives. The energy required to move the volumes of air through an absorber and to regenerate the CO2-absorbing solvent would be cost prohibitive. And the capital cost would be mind boggling. I am sorry to say that the amount of misinformation here is very high, and quite naive.

A better solution is to gasify biomass to synthesis gas (carbon monoxide and hydrogen), shift the CO with water to CO2 and hydrogen, and capture the CO2 while the shifted synthesis gas is at pressure and concentrated. At least you get some energy from the biomass while storing carbon in either saline aquifers or depleted oil fields.

Of course, one would only capture CO2 if you bought into AGW, which at this point, I do not. Fire away!

Erich J. Knight:

March 31st, 2008 at 8:52 PM

The co-benifits of Biochar must also be considered beyond Bio-fuel gain; 3X fertility,17% better water use, fungi and wee-beastie microbes to worms, are sequestered carbon adding to that of the Biochar which in Terra Preta soils has C13 tested to 7000 years.

“we’ve found with some of the biochars in that we’ve had very, very significant reductions in nitrous oxide emissions from the soil; between five- and ten-fold reductions in nitrous oxide emissions.”

Erich

March 31st, 2008 at 9:24 PM

Pat: Re: #68. Yes. That was an error. I should have said 10 cm per year or so.

For a coral growth rate of 10 gm/m2/day and an estimated density of 1.9 gm/cm3 we get an estimated growth rate of 2 millimeters/year, just a little slower than the current rate of sea level rise. On the other hand, the Great Barrier Reef apparently kept pace with an averege rate of sea level rise of about 8 millimeter/year between 13000 and 6000 years ago and individual corals can grow vertically 10 cm/year. http://en.wikipedia.org/wiki/Great_Barrier_Reef#Geology_and_geography
So, perhaps the growth rate estimate I’m using is one that is limited by the present rate of sea level rise rather than what is chemically possible. Our thinking about the rate of ice sheet disintegration has been similarly limited so this is a possibility.

In any case, protecting reef seems like good climate policy and most aspects of protecting reef are also good land use policy and fisheries management policy.

Jim Galasyn:

March 31st, 2008 at 9:34 PM

[C]an [we] remove such a tiny trace gas (CO2) from our vast atmosphere in such a way that any real measurable impact on the atmosphere would be achieved?

A device with an opening of one square meter can extract about 10 tons of carbon dioxide from the atmosphere each year. If a single device were to measure 10 meters by 10 meters it could extract 1,000 tons each year. On this scale, one million devices would be required to remove one billion tons of carbon dioxide from the atmosphere.

Beth S:

March 31st, 2008 at 10:12 PM

Air Capture of CO2….ummm… that’s what trees do if I’m not mistaken, take CO2 + light + H2O = cellulose. You can just cut down the tree and drop it in a nice oxygen-poor swamp or deep bay where it won’t rot, and voila! CO2 captured. THat’s how the coal and oil got there in the first place. So… why go to all this bother of this “air capture” thing when it’s already being done all over the place? Is there something I’m missing here?

pwchase:

March 31st, 2008 at 10:20 PM

“emissions from small dispersed sources” Seems as if that is similar to small dispersed units that need carbon dioxide for food. Trees, grass, cereal grains…..

Martin Vermeer:

April 1st, 2008 at 2:26 AM

Re #70 DBrown: ridiculous, eh? But plants (the green variety) are doing it all the time. At a capacity dwarfing your calculation.
Challenging? Yes. But “impossible” is a term to be used very judiciously. You remind me of the scientist AD 1900 writing that “objects heavier than air will never fly” while a bird was flying past his window :-)

Ray Ladbury:

April 1st, 2008 at 7:44 AM

#53 G.R.L. Cowan, I’m sorry. I should have been more specific. When I said that emissions from diffuse sources precluded a centralized efficient plant, I was speaking in comparison to point sources. Concentrating CO2 from a concentration of 380 ppmv in air to anything like the concentrations needed in solution to make this effective will not be an efficient process. I do not dismiss the technique out of hand, just because the problem of non-point source emissions is so difficult to solve, that we may well be desperate enough to buy time that we’ll try and make this work. However, I think you’ll agree that this does not constitute “low-hanging fruit”.

JSL:

April 1st, 2008 at 10:00 AM

Great job Frank! The most concise overview of air capture yet.
-JL

April 1st, 2008 at 11:18 AM

Re #70 Where DBrown writes “No person with any knowledge of statistical thermo really thinks that we can remove such a tiny trace gas (CO2) from our vast atmosphere in such a way that any real measurable impact on the atmosphere would be achieved?”

I think that is true if you are talking about engineering, but Nature is pretty efficient at absorbing the small concentrations of CO2 using photosynthesis. If we grew more plants and stored the carbon rich material they produce we could reduce the atmospheric CO2 that way.

The problem is that we have to store the produce in an anoxic environment to prevent it reverting to carbon dioxide. This could be achieved by sinking it in water or mud. We could even start now by burying cardboard, other packaging materials and wood rather than burning them wastefully on rubbish dumps.

If there is a problem with finding burial places, we could store them above ground in deserts, or re-grow trees in temperate regions. Trees have the advantage that they store the carbon, and that they absorb carbon over a much greater height than grasses or other crops.

April 1st, 2008 at 12:14 PM

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April 1st, 2008 at 12:28 PM

I am flummoxed as to why a crude technological solution is being proposed when we have a biological solution – plants. Far better to encourage the growth of fast growing plants and sequester their biomass. The solution is cheap, self reproducing and looks quite nice too. Building large facilities that mimic SciFi terraforming ideas is not likely to be an economic approach. If you want to spend money of research, spend it on biotechnological ways of improving photosynthetic efficiency.

Phil Scadden:

April 1st, 2008 at 3:13 PM

#30. Round here, we naively discussed an idea that increased shellbed production could be used as a carbon offset but people on this site kindly showed me the error in this.

When you precipitate CaCO3, then yes, you bind a CO2 molecule, but you alter seawater chemistry so it hold less CO2 (pH buffering) and so CO2
is also released.

The rate that reef/shell precipitation truly binds CO2 is dependent on a Ca flux from weathering into the ocean. If you could find a way to speed that process then yes.

April 1st, 2008 at 3:26 PM

#65, for many years the Canadians operated thorium reactors (CANDU). It was great if you like hydrogen sulfide (needed to separate D2O from water, so yes, it can be done.

Lawrence Brown:

April 1st, 2008 at 4:09 PM

The President has announced that he’s going to refocus US energy policy on conservation, efficiency and renewables, embrace the principles of Kyoto and place a cap on carbon emissions.
Also Happy April Fool’s Day!

Paul Dietz:

April 1st, 2008 at 4:31 PM

The bottom line is that there is a dilution factor beyond which a point of economic “no-return” is surpassed for which it doesn’t make sense (e.g., low-grade uranium ore, uranium in sea water, low-grade iron ore, or in this case, CO2 in air), to expend energy to recover it. This is without even mentioning the embodied energy in the equipment used to carry out the process.

The thermodynamic minimum energy required for the extraction goes only as the log of the dilution, so your claim is rather dubious. Indeed, for uranium extraction from seawater on adsorbing polymers the energy needed to liberate the U from the saturated polymers is only a small fraction of the energy embodied in the U itself (even just counting the fission energy of the 235U, not the 238U).

This is a joke? No person with any knowledge of statistical thermo really thinks that we can remove such a tiny trace gas (CO2) from our vast atmosphere insuch a way that any real measurable impact on the atmosphere would be achieved?

It may not be economically feasible, but vague and incorrect appeals to the laws of thermodynamics do nothing but demonstrate you haven’t though enough about the issue. Indeed, simply observing that nature itself will exothermically react the CO2 with minerals over long enough periods of time shows that thermodynamics alone is not the showstopper.

BTW, the volumetric concentration of inorganic carbon in seawater is greater than that in air, so it may make sense to remove the inorganic carbon from there instead (allowing the oceans to continue to draw down atmospheric CO2 without saturating or getting too acidic.)

should read ” 150 kilograms per capita- processing more than twice our weight in air each day seems within civilization’s economic bounds “

Jim Galasyn:

April 1st, 2008 at 6:15 PM

RE the question CL’s about thorium in 65, I don’t know, but there’s a new subthread at The Oil Drum, with the usual spirited debate.

April 1st, 2008 at 9:20 PM

Martin at comment #40, liquid CO2‘s density depends on pressure and temperature, but is usually much less than the solid form. In my informal article on it, I note that already to get oil out people pressure the CO2 into a supercritical fluid; this has roughly 1/234th the volume of the gas at standard temperature and pressure.

A further point is that this is not a trivial or zero-energy process; if you captured the CO2 from a coal-fired power station, it’d take fully one-third the power it produced to be able to liquefy the CO2. So if all our coal-fired plants had CCS, we’d have to either reduce our power consumption from them by 33%, or else have 50% more generation capacity.

If we’re able to just reduce our power consumption by a third, then surely we should go ahead and do that? We’d then reduce our emissions by a third, too. That then buys us some time to actually make CCS work, to put in renewables and so on. Of course, if we decide that reducing consumption is impossible, then we must build more power plants to make electricity to be able to clean up the mess from the existing power plants… Seems like a bit of a merry-go-round.

The numbers become much better for natural gas and the like. But coal-fired is the most common type of fossil fuel burning power station in the world, and of coal, oil and natural gas, we expect coal to peak last, so it seems fair to take the coal generation as the baseline.

It’s a crock. Burn less stuff.

Thomas:

April 1st, 2008 at 10:26 PM

Go back to comment #53. Basically what is needed is to simply crush a bunch of rocks of the right kind, and spread then out to a depth shallow enough that the CO2 is absorbed within a few decades. The problem is that the quantity would need to be similar to the volume of oil we use per year (3-4 km**3), I don’t know how feasible this is, clearly it would mean disturbance of many square KM**2 per year of desert. The main energy cost are the explosives for breaking up the rock, and to push it around. Chemistry, and time do the rest for free.

Of course as in the exercise to design a solar powered home, the most cost effective thing to do is to first pursue a high degree of energy efficiency. In our case that can be supplemented by low carbon energy (nuclear and/or renewables).

I suspect we have a modest amount of cheap CO2 absorption capacity, such as biochar, and possibly ocean fertilization, but this low hanging fruit is unlikely to be of sufficient volume to constitute more than a modest wedge or two of the needed amount.

A note on burying CO2 for enhanced oil recovery. That Canadian experiment claims to get 6barrels of oil per ton of CO2. How much CO2 does 6barrels (approx 250gallons) of oil contribute when it burns. Oil field burial for EOR is really a way to reuse the CO2 in the form of fuel.

Harold Ford:

April 2nd, 2008 at 1:06 AM

I do feel like a broken record: I’m sure man can mass collect CO2, however plants are much more efficient at the capture. In fact, if a plant grows it is getting its extra mass from CO2. Plant growth equals capture of CO2, simple. Find a weed or grass that does not deplete the soil and that grows quickly, trim it often (I’ve also thought of using trees, trees are good for up to 30 years, after which they should be cut down and replanted). Place the trimmings in a nearby container to store the carbon. It is cost effective, you don’t have to move it very far, it takes a little work and the carbon is contained until the trimmings rot away to nothing. The problem with carbon is it oxidates creating natural gas, so burying it is a simple solution, or use it as fertilizer. The idea of making a process that is more costly smacks of big business: you may make a large sum of money, but can you eat it? I suppose you could burn for heat.

Nick Gotts:

April 2nd, 2008 at 5:07 AM

RE #74 [Edward Greisch] “Thorium can be “bred” into uranium 233 by putting it into a reactor. This is just like making plutonium from uranium 238. Uranium 233 is fissionable just like U235. Since there is more that twice as much thorium as uranium in the world, breeding thorium into U233 multiplies the available nuclear fuel by several hundred times. Likewise for breeding plutonium from U238 and using plutonium as reactor fuel. Since only 0.7% of uranium is U235, the rest of the uranium is wasted unless breeding and reprocessing are allowed. Thorium as a source of fissionable uranium is indeed an excellent idea. The problem is paranoid people.”

No, the problem is the close connection between nuclear power and nuclear weapons. Plutonium and U233 are both excellent nuclear weapons material – or if you don’t have the technology for that, just add a little to a conventional bomb and let it off in a city centre. Not many deaths, but one hell of a clean-up bill. Yes, if none of the alternatives work out, we’ll have to go to nuclear energy on a large scale. But pretending there are no serious problems with it is just foolishness. Sorry to be a bore about this, but as long as Edward Greisch and his ilk keep putting out this “paranoid people” line, without tackling the weapons connection, I’ll keep responding.

Ray Ladbury:

April 2nd, 2008 at 7:32 AM

For all those who say this is impossible as well as all those contending that it is easy–you really should look into this matter before commenting. There are no physical laws being violated. In fact, what Frank is suggesting is just accelerating the geologic mechanisms that take CO2 out of the air. This is a more permanent solution than, say, biochar and other related schemes, since it can be difficult to store the carbon in a way that is stable. Coal beds are about the most efficient storage solution, but we seem bent on digging those up and releasing the carbon.
At the same time this is a very difficult problem–getting any acceleration requires concentrating the CO2 in some way, and that’s bound to cost energy. Even so, the problem of diffuse sources of pollution–any pollution of water, air, land…–is a very difficult one. I do not think we can dismiss this solution out of hand. As Frank implies, we need to go after the low-hanging fruit first–conservation, renewable energy, etc. I do not think that this will be enough to get us out of the soup, and we will have to then look at more difficult options. It is certainly not too early to start thinking about these. If you haven’t sat down and done the math, don’t jump to the conclusion that you’ve solved the problem.

C L:

April 2nd, 2008 at 8:24 AM

Thankyou for several helpful comments re thorium reactors.
I notice some folks put faith in planting trees to take up CO2. Nice idea, eh. They are often so very beautiful, contribute to the hydrological cycle, provide habitat, fruits, nuts, timber,etc. But as a solution ? We can’t even look after the forests we already have, nor reconstruct the complex oldgrowth ecosystems that are the most efficient at utilising particular areas. You plant your new forest. The climate changes. The trees will die…http://www.time.com/time/printout/0,8816,1725975,00.html

Paul Dietz:

April 2nd, 2008 at 10:19 AM

#94:

A further point is that this is not a trivial or zero-energy process; if you captured the CO2 from a coal-fired power station, it’d take fully one-third the power it produced to be able to liquefy the CO2.

You are being misleading. This is the total energy cost using current off the shelf CO2 flue gas separation technology. This includes the stripping the CO2 from the flue gas, not merely compressing and liquefying the separated CO2. Other technologies (such as IGCC, or ammonia-based flue gas CO2 separation) promise considerably lower energy overhead.

April 2nd, 2008 at 10:38 AM

Phil: (#88) Thanks for pointing that out. I’d appreciate a link to the discussion. It seems to me that since the anticipated growth is dependent on sea level rise, then some slight increased solubility owing to the freshening of the oceans could be anticipated.

I expect that we have already provided the oceans with more than enough calcium owing to soil erosion from farming. Lack of sunlight from turbidity and silting or lack of oxygen from hypoxia seem to be the current limits we are setting, along with an unsuitably rapid change in water temperature.

David B. Benson:

April 2nd, 2008 at 12:14 PM

Edward Greisch (74) — If you go back through the comments from the beginning, yoou will find my (longish) post on biocoal.

Frank Zeman:

April 2nd, 2008 at 12:26 PM

Some more comments:

(54) The electric route, as proposed by LANL, tends to consume at least as much electricity as the thermal process we’ve proposed. I guess the challenge for nuclear systems is to establish a cost for unsubsidized electricity that includes waste disposal. One interesting development on the nuclear front is the PBMR reactor taking shape in South Africa (www.pbmr.com). Certainly it’s likely that a suitable wind site exists to run the electric process. Also a suitable solar thermal site may be feasible.

(58) The pressure at the end of the process is 80 bar, suitable for storage. The 37 kJ sounds right for the thermodynamic minimum but in practice it is much higher. To lower the output pressure to 17 bar might chop 20 kJ off the process.

(59) Absolutely, capture from power plants and industry will likely be cheaper. Getting those sources can capture about 50% of current emissions, air capture is concerned with the portion of the remainder that cannot be eliminated by efficiency and renewables.

A general note on biomass. Biomass systems would likely be cheaper than Air Capture at current biomass costs ($60/tonne). As mentioned, you run a power plant off biomass, get green power and capture the CO2. There is a great quote from the IPCC WG3 report that states roughly that any biomass solution implies the resolution of issues surrounding food production, water for irrigation, biodiversity and land use change. Witness the rise in food prices brought on, in part, by the ethanol boom. Global bimass productivity is estimated at 60 Gt carbon per year. We now consume 8 Gt C or so for energy and agriculture uses 10% of the land (or so). So what are the effects of devoting around 25% of the global biomass production to intensive agriculture? Who gets to decide when you grow food and when you grow fuel? Air Capture can also get CO2 at a rate at least 100 times faster, per unit land area, than biomass growth. I do think that agricultural wastes should be used with attention so that the waste does not become more valuable that the product.

Storing carbon in the surface environment, as biomass or biochar, is feasible but high risk as it is very labile or mobile. If we charge a field with carbon and then it is tilled then the carbon goes back to the atmosphere.

As always, the first thing is efficiency, capture and power plants and continued growth in solar panels.

Phillip Shaw:

April 2nd, 2008 at 12:43 PM

I have been trying to post what I feel is a cogent and insightful comment but it keeps getting kicked out as spam. For the life of me I can’t figure out why. Frustrating! The error message says to contact “us” if it continues to be a problem. Who is this “us” of which it speaks?

April 2nd, 2008 at 12:56 PM

for many years the Canadians operated thorium reactors (CANDU).

The CANDUs are still operating, indeed a new one started up in Romania last year, and a clone in India, but have never run on anything but plain UO2.

It makes sense that a never-run CANDU core could start up with a small fraction of its fuel bundles containing instead ThO2, and as it cooked slightly increase this small fraction, but CANDUs have always been independent both of uranium enrichment and of fuel reprocessing, and without reprocessing, fractional substitution of uranium with thorium would be the extent of it.

40 billion barrel-of-oil-equivalents per year — ten times the use rate — seems to be the recent rate of discovery of uranium deposits, driven by a U price of almost $2/BOE, about a year off a brief spike over $3.

Adding a little complexity to core management and fuel fabrication in order to save a third or so on uranium hasn’t, I guess, seemed worthwhile, and probably won’t seem so any time soon. (Spent thorium, i.e. thorium that has been converted to 233-U and then to fission fragments, does not differ in any essential way from the mix, in existing CANDU spent fuel, of fragments from the fission of about 60 percent 235-U, 40 percent 239-Pu.)

Ike Solem:

April 2nd, 2008 at 1:30 PM

Really, this whole issue has to be viewed in the context of carbon cycle changes as global warming proceeds. Thus, readers might want to look at a previous post on RC:

We know that the Earth’s biosphere has been in photosynthetic and respiratory balance, more or less, during the last 10000 years or so (because atmospheric CO2 was steady), even though that balance is on the order of 100 gigatons of carbon back and forth each year (humans add some 6-7 gigatons of carbon per year). The main issue is that warming soils, permafrost and oceans could start outgassing CO2 that has been locked up for several million years as methane or organic carbon. The system will eventually reach a new equilibrium, with sea levels many meters higher than they are now, over an unknown time period – 100-1000 years?

If there is such a tipping point in the carbon cycle, such that a complete halt of human CO2 emissions would not halt the (slower) rise of CO2 in the atmosphere, then we should try very hard to avoid it.

In order to do that, we have to stop adding fossil carbon to the atmosphere, and that means coming up with alternative energy supplies to replace fossil fuels. There is literally no practical way to capture carbon from coal combustion. As the author points out:

3) The best estimates for the energy consumption of AIr Capture is 350 kJ/mol CO2. I think we can get that down to 250. The heat released from coal is 400 kJ/mol CO2 with all other fuels higher owing to the hydrogen present. While not super efficient, we regularly accept only 35% conversion of coal to electricity.

Practically, what that means is that we would have to build a massive new facility next to each coal-fired power plant on Earth, which would be dedicated to air capture, and which would consume, according to best estimates, 87.5% of the energy produced by the coal fired power plant, but, considering process inefficiencies (i.e. that 35% coal-to-electricity conversion), you’d be lucky to break even. It sure looks like a perpetual motion machine. The complete failure of the highly promoted “FutureGen” coal-carbon-capture plant (after something like $1 billion was dumped into it!) is more evidence that this is a hopeless quest.

It’s a bit like asking car companies to build cars that capture all the CO2 emitted by the internal combustion engine and store it all as carbonate bricks in the trunk as you drive down the road. Any auto engineer would laugh in your face at such a request – but we have many university departments devoted to this nonsense, such as Stanford’s ExxonMobil-funded and controlled “Global Climate and Energy Program” (which Exxon executives claimed was evidence of their support for renewable energy in the recent Congressional hearings).

Sally Benson, executive director of the Global Climate and Energy Project (GCEP) and professor of energy resources engineering: ”But the idea that we can take fossil fuels out of the mix very quickly is unrealistic. We’re reliant on fossil fuels, and a good pathway is to find ways to use them that don’t create a problem for the climate.”

Any money spent on research into carbon capture and sequestration would be far better spent on the energy supply side in developing solar PV and thermal energy conversion plants, as well as in improving national electricity grids, setting up offshore giant wind turbine farms, and developing a variety of photosynthesis-based fuel production strategies. On the energy demand side, we should be focusing on energy conservation, fossil fuel-free agriculture and industry, efficient technology, good housing, and so on. Carbon capture is nothing but fool’s gold.

Jim Cripwell:

April 2nd, 2008 at 1:49 PM

Ref 75. What about solar cycle 24 shows no signs of getting going? I agree we need the debate on different data sets for global temperature anomalies.

Alexandre:

April 2nd, 2008 at 3:37 PM

The debate has its usual heat here, but it´s good to see a debate over possible solutions. Thank you RC people.

My non-scientific opinion: keep it simple. Grow trees, lots of them, cut them down, prevent them from decaying or releasing its carbon to the atmosphere- water, confinement, mummification, whatever.
Then repeat the process growing new ones. Maybe fertilizing the soil with Terra Preta would give it an extra kick.

Oh, and leave the natural forests alone.

April 2nd, 2008 at 3:43 PM

RE #96, I know just the plant/tree for carbon capture, at least for tropical, subtropical, and arid places that don’t get killing frosts (at least not more than once in 5 or 10 years). It is the moringa tree. The following site has a great PowerPoint on it (& you can google for more sites) – http://www.treesforlife.org/our-work/our-initiatives/moringa

We have them growing in our back yard in S. Texas (they are originally from India). They shoot up to 20 to 30 feet or more within a few years. We keep cutting them back so the fruits (drumsticks) won’t be so high, and we plant the branches, which shoot up to big trees in a few years. The leaves can also be eaten as spinach, and they increase milk production in lactating mothers and cows. The leaves and fruit are extremely nutritious, plus I think oil from the seeds can be used as biofuel (they are experimenting on it), and the seed pods and other parts can be used as cellulose biofuel.

My husband doesn’t have the heart to throw away the pruned branches and has kept planting them, so we’re going to have a back yard forest after some time. We did have a killing frost a few years back, and the trees died down, but then sprang back up 20-30 feet within a few years. It grows in poor soil, drought conditions, or swampy conditions. Can be intercropped with other trees and plants, and doesn’t take up much space, since it grows straight up.

I consider it one among many many many solutions to global warming (& world hunger).

First principle is reduce (through energy/resource conservation/efficiency & good old “just reduce” on the non-essentials), then reuse, then recycle & buy recycled, then use alt energy, and if you have a bit of land in a warm enough area, plant moringa trees. Meanwhile the air-capture folks should be in full swing doing their part, as well. We need all these solutions and many more that might be thought up if we had an atmosphere conducive to eco-innovation.

Anyone else here know about the moringa tree?

April 2nd, 2008 at 6:00 PM

#75 GlenFergus: in the meantime this page at the UK met office may be of some help.

There are already claims out there that the temperature trend has flattened or even gone down. If you do a linear regression on Jan 2001-Feb 2008 of HadCRUT3 for example the trend is slightly down but the correlation coefficient is something like 0.05 which is not far off random.

All you can really say about such a short period is that natural variability overwhelms the long-term trend, which remains up.

If an article is written could I suggest something like “What if you can type into a spreadsheet but are a scientific illiterate?” Maybe a bit too confronting…

Paul Dietz #91: Interesting idea, getting the carbon out of the sea. Given the concerns about ocean acidification (more correctly, becoming less alkaline) this could be a nice idea. Attack one of the more serious problems directly.

Harold Ford #96: Plants are good at capturing carbon but the problem is that we are extending them beyond their design limits already (recalling that eras when CO_2 was higher were on a geological timescale away from now, i.e., evolution had time to optimize plants to the new environment). Plants are generally not CO_2 limited, otherwise they would be handling the problem already. If the problem persists of course there will be a shakedown (aka mass extinction event) where the plants better adapted to higher CO_2 will eventually dominate. Some of the plants which don’t like higher CO_2 include grain crops (from memory, maize/corn is one; wheat and rice can use more CO_2). Your idea may have some merit except that increased CO_2 is not the only variable, so is climate change. This could radically reduce areas of viable farm land, so converting the necessary big areas over to growing a weed would be problematic. Find something that thrives in the oceans on high carbon, and dies back and sinks to the bottom when carbon levels drop, and you may have a solution — thus nearly tying together your idea and Paul Dietz’s.

Don’t confine your thinking to the macroscopic: some bacteria are photosynthesizers, and bacteria did the initial job of oxygenating the atmosphere. Some interesting stuff in Science Daily on how that became possible.

Any comment from the real climate scientists? Could any of this work?

Ferris:

April 2nd, 2008 at 9:06 PM

#55 David Benson says: “Biochar makes a most useful soil amendment. But about half of the carbon returns to the active carbon cycle with a few years. Moreover, the storage time of the remainder is unknown.”

David, as long as the soil is not disturbed, black carbon is very stable within the soil. Also, the storage time is very well known. In particular, the black carbon contained in the Amazonian Dark Earth’s, because of the particle size, is very stable (on the order of thousands of years).

Even the black carbon produced from the burning of the tallgrass prairie’s here in the U.S. is very stable, despite the fact that it’s easily oxidized because of it’s small particle size.

Philip, this statement is not true. Corn production will increase as CO2 concentrations increase, just not as much as wheat and rice.

Chuck Booth:

April 2nd, 2008 at 9:19 PM

Re # 70 DBrown “Is this a joke?”

Apparently not:

Carbon capture and storage (or sequestration) is receiving increasing attention as one tool for reducing carbon dioxide concentrations in the atmosphere. In his Perspective, Lackner discusses the advantages and disadvantages of different methods of carbon sequestration. He advises against sequestration in environmentally active carbon pools such as the oceans, because it may merely trade one environmental problem for another. Better sequestration options include underground injection and (possibly underground) neutralization. Taking into account carbon capture, transport, and storage, the author concludes that in the short and medium term, sequestration would almost certainly be cheaper than a full transition to nuclear, wind, or solar energy.

Chuck Booth:

April 2nd, 2008 at 9:21 PM

Re # 63 JCH (and #71 Jim Galasyn’s response)

As Jim suggested, sequestering CO2 in the deep ocean is not such a great idea:

Efforts to reduce carbon dioxide emissions are increasingly looking to the oceans, either through iron fertilization programs …or through CO2 injection into the deep sea. In their Perspective, Seibel and Walsh investigate how such deep-sea disposal may affect organisms that live in these environments. They warn that even small perturbations in CO2 or pH may have important consequences for deep-sea ecosystems and for global biogeochemical cycles. Detailed studies into these effects are needed before the risks and benefits of deep-sea carbon storage can be assessed appropriately.

JCH:

April 2nd, 2008 at 10:29 PM

113. Re # 63 JCH (and #71 Jim Galasyn’s response), Chuck Booth

Your concerns were why I asked if anybody was working on containerization. The articles I read were describing either injecting liquid CO2 into deep water, or sinking blocks of dry ice.

This paper is more recent, and they are describing using the seabed as a container:

Using the pressure and temperature to fence it in sounds interesting,

Rod B:

April 2nd, 2008 at 10:34 PM

I think I recall previous threads/posts here concluding that while we want and need all the trees, trees per se are not that marginally productive in picking up CO2, and planting more is neither timely nor effective. My old calculations said an average tree will absorb and sequester (for now) about 1100 kg of CO2 over roughly 30 years. [Ballpark figure, as there is considerable variability among species of both amount (600 – 1500 KG or more) and time (15 – 100 years)] Four hundred of these trees in a hectare (one every 25 sq. meters) would pick up the CO2 exhaust from 12 vehicles driving 15,000 miles per year each for five years getting 18MPG. Amplified by the 5-year output to 30-year absorption rate (would it ever catch up with the emissions?) or not, this seems like a gazillion trees have to be planted to make a dent.

Lynn’s moringa trees seem pretty good. And it’s true (we suspect) that a goozillion bacteria had a large macro effect as Philip points out. I always thought the very fast growing with very fast plant metabolism (eating CO2) hemp might be good — one could use the fibers for cloth and paper and maybe get long-term sequestering; still probably couldn’t smoke the other parts, though. None-the-less all seem like drops in the vat.

Jerry Toman:

April 3rd, 2008 at 1:14 AM

Ultimately, this is about “allocation of resources”. It doesn’t make sense at this point in time to invest in “air capture” as long as we put CO2 into the air from sources of far higher concentrations. The one exception is effort expended in preventing forests which now store carbon from becoming “biofuel plantations”.

If we use our resources to extract Convective Available Potential Energy from the troposphere instead, this will allow us to phase out fossil fuels by 2020. This will take only a minimal investment and a couple of years of effort dedicated to development of the Atmospheric Vortex Engine. (www.vortexengine.ca)

6000 times more CAPE is dissipated irreversibly than the rate at which humans produce and consume mechanical (electric) energy via fossil and nuclear fuels.

Meanwhile geothermal and waste heat (including warm seawater) can be used to supplement the CAPE derived from the troposphere and renewed by the sun each day.

April 3rd, 2008 at 1:31 AM

Re #94 Kiashu:

Martin at comment #40, liquid CO2’s density depends on pressure and temperature, but is usually much less than the solid form.

Actually it’s around 1000 g/litre (only slightly pressure dependent), so multiply my figures with 1.6. Still reasonable. Supercritical is a different thing.

BTW you are accusing a large number of honest, competent and hard working scientists and technologists of being involved in “a crock”. Looking at your informal article, I don’t see much to match that professionalism. I don’t know about you, but if I were one of those folks, I would have a problem with your attitude… please help to keep this forum minimally civilized.

April 3rd, 2008 at 1:35 AM

Re #104 Phillip Shaw: WordPress has the hateful habit of spam filtering on parts of words. Like “special-ist” containing the blue pills we all love to hate :-)

Just put hyphens in the problem words.

Nick Gotts:

April 3rd, 2008 at 4:21 AM

RE #106 [Ike Solem] “There is literally no practical way to capture carbon from coal combustion. As the author points out:

3) The best estimates for the energy consumption of AIr Capture is 350 kJ/mol CO2. I think we can get that down to 250. The heat released from coal is 400 kJ/mol CO2 with all other fuels higher owing to the hydrogen present. While not super efficient, we regularly accept only 35% conversion of coal to electricity.

Practically, what that means is that we would have to build a massive new facility next to each coal-fired power plant on Earth, which would be dedicated to air capture, and which would consume, according to best estimates, 87.5% of the energy produced by the coal fired power plant, but, considering process inefficiencies (i.e. that 35% coal-to-electricity conversion), you’d be lucky to break even.”

Ike, this is nonsense. What is proposed for CCS from power stations is NOT air capture.

pete best:

April 3rd, 2008 at 4:26 AM

Re #106. Ike, you seem very knowledgable on the subject but can you tell me your relevant qualifications in the field of carbon capture and climate science in general. Are you a interested layman or a scientific professional.

I ask because the royal society in the UK has written to the UK Government asking that any new coal fired power stations have CCS fitted and hence they must think the technology is viable. However you do not. Who is right?

C L:

April 3rd, 2008 at 5:12 AM

Re #108/9.

It seems to me that there is a fundamental philosophical distinction to be made between natural approaches to the problem (trees) and technological approaches (manufactured gadgets to scrub air). Natural systems produced the relative equilibrium and harmony that we found when we evolved.
Technologies are what has got us into this present mess.

Over-simply put, if you’ve got a problem of long grass around your house, you can either buy a noisy red mower to annoy your neighbours. You’ll have to earn the money to buy it, and for more expense for fuel and parts and maintenance, the manufacturers overheads and advertising, employees pension schemes, shareholders profits, and you’re tied to all the factories that make the bits, refineries, and the shipping networks, the whole rigmarole of international commerce, all of which presently rely on fossil fuels and cause pollution, etc. Then, with planned obsolescence, it’ll break and you’re forced to repeat.
Or, alternatively, you can get something like rabbits, or sheep, or chickens, or geese, that’ll eat the grass, reproduce themselves, and produce food and fertilizer as a handy by product.

I would certainly always be in favour of the latter eco-friendly approach. However, seems to me that we are now in such a global mess and so pressed for time, that all potential good ideas need to be considered, ( even if they look ugly, like nuclear power). There are plenty of them. People are extremely ingenious. The problems appear at the implementation stage. I can just imagine some scam merchant taking up the suggestion of moringa trees and raising funds to buy land, and then they’ll go and wreck some precious swamp with diverse rare species, or cut down ancient woodland, or whatever, and cause much more harm than good. The sort of stupidity that has followed from the misconceived biofuels fiasco is so typical. Anyone remember the East African ground nut scheme ?

Farmers generally think of their crop yields in terms of land area. They need to think about how they can utilise the other dimension; upwards, with trees and climbers, downwards, building soil depth which acts as a storage for CO2 and water. Unfortunately, agribusiness thinks in terms of large scale monoculture to maximize efficiencies. I think it has been established that maximum diversity makes for maximum resilience in the face of climate perturbations. Put simply, if a thousand acres of potatoes is hit by drought and disease, you’re left with bare soil which blows or washes away. If the same thousand acres is covered by ancient woodland, with tens of thousands of species, it can easily cope with extremes. The field of potatoes is probably a net contributor to Global Warming, whilst the oldgrowth forest is one of the micro-units which created the previous stability we enjoyed.

If climate change is very fast, the forests which have evolved to suit particular soil type and local conditions will want to move, to follow the thermocline. They can do this naturally, but it’s rather slow. a few miles a year. Human intervention might help, but usually there will be impassable obstacles, cities, mountain ranges, etc.

Another issue is peat. I believe it’s correct that there is more CO2/methane locked in the UK peatbogs than in all the trees in Europe. How do we conserve peatbogs ? At the moment they are mined for garden compost. If the weather becomes drier, they will release their CO2. Seems to me always preferable to put money into trying to save the natural systems that do the work for free, (like sphagnum moss that’s fixing CO2 while we sleep in our beds), than put money into new technological gadgets. Seems to me that these start ups with a cunning new idea don’t ever do proper carbon accounting, in that they leave out all the associated inputs go along with the enterprise. Bit like folks who say they’ve planted a tree to compensate for an air flight, and think they’re ‘being responsible’ and virtuous. But what about all the hundreds of previous flights over decades ? each of us is responsible for the whole legacy we leave to the future generation. People on this site like to follow scientific logic. Logically, the best answer must be to leave all the coal and oil where it is, at least until we can sort out the CO2 problems. I’m not at all optimistic. I see almost everything that almost everyone is doing is pushing in the wrong direction, despite the efforts of a heroic minority. The real fundamental problem is human nature and politics, and there’s no techno-fix for that.

DBrown:

April 3rd, 2008 at 6:48 AM

Relative to my original post (#70) there seems to be some confusion, so I wish to clarify.

First, my post was not totally serious but was, in a superficial way, only pointing out that the cost effective extraction of atmospheric CO2 as the original author claimed by chemical removal of the gas from the atmosphere is far too energy intensive to be worthwhile.

A few people have posted that plants already do this and they feel that this revelation on their part is significant and (I assume) that this somehow validates chemical/mechanical methods proposed in the original article. All I can say is please explain how this relates to author’s process?

As many have posted, capture at the point sources is far more feasible but then other issues come into play (energy production, storage, transport costs, etc) and need to be addressed in a serious, technical manner, not the silly manner the original author exploited.

As for post #73, comparing the possibility of atmospheric processing to total world population the writer is misguided – last I checked, respiration by people does not process CO2 from the atmosphere into any storable form. Their claim that this proves the idea of atmospheric collection is feasible is simply ludicrous.

As for using algae in the oceans post #113 says it all.

To address the idea of land surface processing using plants, such a massive program would be highly complex but a superficial look does not appear promising.
Relative to areas that fresh water and sun are readily available, most the tree’s that used to do this have been removed and the land is being exploited by humans for very minor purpose like food production, and habitat similar uses.

As for using deserts for algae systems (lots of free solar energy, open land), the creation of vast pond systems would require large inputs of energy (digging/excavation, processing and construction equipment, water pumping/delivery systems, aeration systems, and related support facilities to name the obvious issues) and even if the algae can be converted into fuel (energy content, and transport to market costs?) in order to process sufficient CO2 from the atmosphere to radically affect CO2 climate warming would be highly doubtful (if you think otherwise, please reference a peer reviewed paper showing otherwise. Hand waving is not too useful.)

Relative to power sources for atmospheric capture, some have suggested thorium power plants. I know next to nothing about thorium plants and can only say that to the best of my knowledge, no commercial plants have or ever have been constructed and that would appear to indicate that this is not (currently) viable. Someone knowledgeable in the field should address this issue.
Breeder reactors are a whole other story and can be very dangerous despite the posts by some that indicate that this belief is not based on facts.
A few minor points: the one US commercial breeder plant (Fermi plant, outside Detroit) had a major meltdown and more by luck, did not undergo a nuclear fission explosion. If it had, the city could very well have been destroyed. Breeding nuclear fuel requires very extensive chemical processing that creates extremely radioactive and large amounts of nuclear waste that must be handled, transported and stored. Also, these plants can be used to manufacture material for atomic bombs – hardly what we want every country in the world to be doing.
American designed high pressure boiling water reactors are very difficult to safely operate without massive, complex, highly costly and failure prone systems and while no deaths have occurred in this country from numerous nuclear reactor accidents, I understand people’s very rational fear of these plants.
The Canadian plants (heavy water, natural uranium fuel) are highly safe and compared to US plants, much more inexpensive but they have a problem: these plants require high quality natural uranium and if a lot of such plants are built, getting enough fuel could be a major problem.

In any case, wasting such power plant energy production on CO2 capture is worse than foolish, it is irresponsible. Any none CO2 based energy source should be used to supply power to support people’s direct survival, not diverted in an inefficient manner to capture CO2.

Ray Ladbury:

April 3rd, 2008 at 8:02 AM

Nick Gotts, re: dirty bombs. The main value of a dirty bomb as a terrorist weapon derives more from irrational fear than actual damage–and in any case, Uranium and Thorium would make really lousy dirty bombs due th their high density and the nature of their decays. The Th fuel cycle is more desirable in part because it is more difficult to weaponize the byproducts than Uranium or even Plutonium.
There was a pretty good article a couple of years back in American Scientist on the process. I do not discount the difficulties associated with nuclear power–storage of wastes and proliferation are not trivial problems. However, in some ways, the waste problem is easier than it would be for, say, a coal plant precisely because the pollution is from a point source. Nuclear power would not be my first choice as an alternative energy source, but if it came to a choice between nuclear and coal, I think the overall threats from nuclear are easier to manage than the climate threat stemming from coal. CCS could change this balance, but that remains to be seen. I am reluctant to prejudge the outcome, since I view the climate as the main threat facing the continued viability of human civilization over the next century–well maybe second to human stupidity. Cheers, Ray

John Laumer:

April 3rd, 2008 at 8:13 AM

Performing a life cycle inventory on any of the proposed technologies for capture is straightfoward, and has already been done for production of the Kraft process inputs. So there is no need really to speculate. Someone at DOE needs to get the assignment to combine the information and off we go.

An earlier commenter brought up serpentine rock as a carbon sequestration medium. See this excerpt from a post I wrote for TreeHugger.com regarding some limitations.

“…Serpentine rock, as Mg3Si2O5(OH)4,is the California State Rock, and “is found only in areas where oceanic crust is subducted and then pushed up again along fault zones. Worldwide, Serpentine is sporadic in distribution and high in heavy metals, creating rare plant communities on its soils”.

One obvious risk management ‘driver’ is that that serpentine barrens often support rare and/or endangered plant communities. Further, that benefaction and processing of the serpentine rock will produce heavy metal residues; and, it would be essential that these materials be turned into co-products or that magnesium suppliers ensure they are properly disposed of. Both reasons underscore the need to base the system design on a recycling paradigm.”

Nick Gotts:

April 3rd, 2008 at 11:00 AM

Re #123 Thanks Ray – I’ll see if I can find that AmSci article on dirty bombs. But as I understand it, while U233 is more difficult to handle than U235 due to its higher radioactivity, it can still be made into nuclear weapons. I guess the question is – would you want it freely traded to anyone with the money? If not, we’d do best to minimize how much of it there is.

Martin at comment #117 writes that “BTW you are accusing a large number of honest, competent and hard working scientists and technologists of being involved in “a crock”.”

The problem with that is that equally honest, competent and hard working scientists say that CCS is not likely to ever be a significant mitigator of climate change, and that the best thing to do is just burn less stuff.

Tim Flannery’s one example of an honest, competent and hard working scientist who thinks CCS is a crock. I mean, this isn’t like climate change, where it’s pretty obvious that the “scientists” denying it used to be working for the tobacco industry and are many smaller in number than the scientists arguing the data support climate change. With climate change if we want to do an appeal to authority, well 1,000 or more to 1 seems pretty good.

With CCS, it’s rather less than that in favour.

That’s the problem with the argument from authority; what do you do when two equal authorities disagree?

Consider for example uranium mining on Navajo land in the US, gristmill mentions the LA Times doing a series on it recently. At the time a big swag of scientists – honest, competent and hard working – said it’d be completely safe for the Navajo. A few decades on and they’ve got animals born without eyes, double the pre-mining rate of cancer, and so on. Now a mining company wants to go back in and dig up some more uranium, and there’ll be a legal battle, where one lot of honest, competent and hard working scientists say it’s horrible and deadly, and another lot of honest, competent and hard working scientists say it’s all harmless.

Just because an honest, competent and hard working scientist is involved does not mean it’s a good idea.

All you’ve done is to take offence at my tone, and my temerity in daring to question that any honest, competent and hard working scientist could ever be wrong. You’ve not spoken to my substantive points:

– liquefying the CO2 from coal-fired plants will require at least one-third the energy those coal-fired plants generate.
— does this mean we’ll reduce our non-CO2-liquefying electricity consumption by one-third, or that we’ll build 50% more capacity?
– CCS has not been fully successfully trialled anywhere.
— the CO2 for enhanced oil and gas recovery came from industrial plants manufacturing it, not from coal-fired stations, cars, etc; so the capture technology is unproven and indeed largely untested and uninvented
— CO2 injected has leaked in every site
— CO2 injected into coal seams is designed to released CH4, a stronger greenhouse gas than CO2, and this too will leak; already 5-10% of the natural gas we use leaks before end use
— CH4 generated from CO2 injections into coal seams will be burned, releasing more CO2, so this may not actually be a net sequestering of carbon; no calculations have been made public
– how are we going to capture the carbon emissions from vehicles, deforestation, livestock, rice farming and so on?

Further points, not mentioned in my article, would be the decades required for a rollout of such technologies, even assuming they could be made perfect without further research or effort. I look forward to projections from those sponsoring CCS showing that we could achieve substantive reductions in emissions as a result. But I’ve not seen those projections. No-one seems to have said, “it will take this long, cost this much and achieve so-and-so.”

I look forward to a response to my substantive points. If they’re so unprofessional and stupid, it really shouldn’t be difficult. Robert in comment #34, for example, made a comment about the large volumes available, he easily knocked me down on that.

I mean, if I come in with something like, “oh but what about solar forcing?” then I’ll be demolished in moments, because I’m so plainly wrong. So, show me how I’m wrong in this.

re #21 Secondary effects from more nuclear power plants will add to what “Nature will do the job for us” … and greatly reduce AGHG emissions in the long term.

April 3rd, 2008 at 11:38 AM

“A key comparison illustrates the daunting scale of the challenge. In 2005
worldwide CO2 emissions amounted to nearly 28 Gt; even if were to set out only a modest goal of sequestering just 10% of this volume we would have to put away annually about 6 Gm3 (assuming that all of the gas is compressed at least to its critical point where its density is 0.47 g/mL). The current extraction of crude oil (nearly 4 Gt in 2005) translates to less than 5 Gm3. Sequestering a mere 1/10 of today’s global CO2 emissions (focus – they just look at one little bit. I mean, that’s how science is done. Nobody measures or tests or experiments on everything. They just pick a bit that interests them and have a look at that.

So in doing that, it can be easy for them to miss the big picture. Busily focused on measuring the rates of CO2 adsorption in anthracite, they might not ask themselves, “okay, if this all works well, how much of the coal-fired plant’s power are we going to need to deal with its CO2?” It probably won’t even occur to them.

Likewise, it does not seem to have occurred to anyone except Smil just how much infrastructure a worldwide sequestration project might need. And it turns out it’s quite a lot, and it’s not really plausible that we’ll build it all.

He says further, and I largely agree,

“I must hasten to add that underground CO2 sequestration in the service
of secondary oil recovery is most desirable, as is any form of plant-bound
sequestration, ranging from a gradual build-up of soil organic matter to
massive planting of trees. But beyond these highly desirable actions the stress must be on reducing the emissions, not hiding them in an uncertain and costly manner.” [p.21, my emphasis]

I don’t agree that pumping out more oil is desirable, but if it’s going to be pumped out anyway, we may as well pump its pollutants back in.

“The obvious question is why it should be even attempted given the fact
that a 10% reduction in CO2 emissions could be achieved by several more
rational, mature and readily available adjustments. […] Of course, this suggestion is always met with derision and the chances of such a shift are judged to be utterly impossible.” [p.21]

Of course if people know of techniques for sequestration of the CO2 using substantially less infrastructure than Smil suggests, I’d certainly be interested in hearing of them, and I’m sure a few large oil, coal and gas companies would pay good money for those ideas.

April 3rd, 2008 at 11:49 AM

RE #115 & “Four hundred of these trees in a hectare (one every 25 sq. meters) would pick up the CO2 exhaust from 12 vehicles driving 15,000 miles per year each for five years getting 18MPG” & “all seem like drops in the vat.”

Yes, it’s an uphill struggle, but never give up, never surrender. First of all, men & women, we need to stop driving our cars 15,000 miles a year (unless we’re traveling salespersons). We need to move closer to work/shops/school. We need to take more public transportation, bicycle, and walk (and smell the roses along the way, & reduce our heart disease, cancer, and diabetes, etc.).

We need to get much more than 18 mpg — we need those plug-in hybrids, live within 5 miles of work (preferrably one, so we can walk), have wind or solar electricity & drive on the wind/sun (my 100% wind-powered GreenMountain electicity is actually cheaper than coal/gas powered electricity). We need to turn off our motor in drive-thrus, keep tires inflated, avoid jack-rabbit starts & reckless driving.

And we need to plant more trees. And do air-capture.

There used to be a book, 50 SIMPLE THINGS YOU CAN DO TO SAVE THE EARTH. We need a new book (online, not paper print — save those trees), 1001 THINGS YOU CAN DO TO MITIGATE GLOBAL WARMING. Then as with the 50 SIMPLE THING series, 1001 THINGS YOUR BUSINESS CAN DO TO MITIGATE GLOBAL WARMING. Then 1001 THINGS GOVERMENT CAN DO TO MITIGATE GLOBAL WARMING. Then 1001 THINGS YOUR CHURCH & SCHOOL CAN DO TO MITIGATE GLOBAL WARMING.

I know taking a hanky for drying hands in public restrooms is less than the proverbiable drop in the ocean, but drops add up, even half-drops. If everyone reduced just one little candle’s worth of of CO2E whenever possible/feasible, what a cool world this would be.

April 3rd, 2008 at 11:56 AM

OT, but just found out about this new TV series in England, THE ELEVENTH HOUR, a present-day investigative thriller about a retired scientist assigned to investigate scientific issues — which involve powerful interests out to do bad. And it has an episode about global warming!!

Be sure to view the preview & synopsis of Episode 3, “KRYPTOS,” which is about a climate scientist who says he has proof of some imminent climate catastrophe, and is claiming people are out to do him in….they think he’s paranoid, until he goes missing….

Maybe RC scientists can view it (those who might have access to it) and give their scientific assessment.

Hope they bring the series over here to the U.S.

David B. Benson:

April 3rd, 2008 at 12:04 PM

Ferris (111) — I encourage you to also read the recent report summarizing what is known about biochar, especially with regard to lifetime of the carbon in the ground. It is a .pdf file accessable via this link:

April 3rd, 2008 at 12:24 PM

Go back to …

comment #53. Basically what is needed is to simply crush a bunch of rocks of the right kind, and spread then out to a depth shallow enough that the CO2 is absorbed within a few decades. The problem is that the quantity would need to be similar to the volume of oil we use per year (3-4 km**3), I don’t know how feasible this is, clearly it would mean disturbance of many square KM**2 per year of desert.

Each 100 gigatonnes of legacy CO2 in the atmosphere would convert to a few hundred km^3 of dust. If this were deposited over tens of millions of km^2 of dry desert, or hundreds of millions of km^2 of a wet desert such as the southern ocean, whose CO2 sponginess you may recall has recently been in the news as getting tired, it would be unobtrusive. Remember, the accumulation would be over a decade or so. I said more about this here, although at that time I didn’t yet know about olivine’s goodness, so thank you for that.

The main energy cost are the explosives for breaking up the rock, and to push it around. Chemistry, and time do the rest for free.

For the comminution of the olivine or serpentinite you want to use mostly electricity, not explosives. I’m pretty sure primary energy to electricity is a much lower-loss conversion than primary energy to explosives, and electric ore crushers had become very efficient by the early 1990s. (The uranium in one piece of average continental surface stuff, if fed to CANDU reactors, would enable those crushers to crush, or “comminute”, five equally heavy pieces.)

(Postings have individual URLs that are hidden in the date-and-time line under the poster’s nym or pseudonym. Try the right mouse button on one and you should find it possible to pluck the URL and put in into a link, rather than telling people to search.)

Phillip Shaw:

April 3rd, 2008 at 12:49 PM

Re #70 DBrown et al:

There is a technology that I haven’t seen discussed much which demonstrates the feasibility of capturing CO2 from the air. Industrial Air Separation Units (ASUs) have been around for decades and are a mature and robust technology which may be worth investigating. The basic process is straightforward: air, either ambi-ent air or a CO2 enriched gas, is compressed and cooled to condense and remove its moisture. The dry gas is further compressed and cooled until the CO2 condenses and can be drawn off for sequestration. For industrial purposes additional stages are used to produce liquid nitrogen and liquid oxygen, but for this discussion we don’t need to go into that. Once the CO2 is removed the air is released. There are several nice aspects to the ASU process. One is that the only ‘waste’ product is reasonably pure water. Another is that a significant portion of the energy spent compressing and cooling the gas stream can be recovered by expanding the CO2-depleted air through a turbine to compress and cool the incoming air.

I envision ASU technology being incorporated into solar powered CO2 capture units designed to be efficiently mass-produced. Thousands of these could be placed in desert areas such as western Australia or western North America and the water they produce could be used to convert desert into arable acreage. Initially the plant yields would be low due to the poor desert soil, but by converting the initial growth into biochar and plowing it back under to improve the soil the land would become more productive. Ideally, this iterative cycle would produce arable land for crops and/or biofuel feedstock. I don’t believe that tree farms are out of the question either. The plant material grown, and the carbon sequestered in the biochar, increase the overall efficiency of this idea. I understand that the CO2 collected would still have to be sequestered but that is true of all carbon capture concepts.

My thanks to Martin Vermeer for helping me navigate the WordPress spam filter. Would you believe the problem word was ambi-ent?

April 3rd, 2008 at 2:59 PM

Re 74 Edward Greisch and 29
In the scheme I am suggesting, the waste heat from very small engines in very efficient cars (about 12 horsepower) would power electric generators that would charge car batteries and feed power to the grid. Thus, the car and the house are arranged for very efficient cogeneration. There is very little equipment cost for plumbing connections that would enable heat transfer to the household and would also enable transfer of natural gas to the car. The key difference from the status quo is the size of the engine and generator in the car. The PRIUS engine is probably too big to be “appropriately sized” for this kind of operation. However, if a new type of high efficiency vehicle were to come about, a very large energy saving could come about.

Ike Solem:

April 3rd, 2008 at 3:39 PM

Nick and pete, I think the car example is a good one. If someone can build a car that has a carbon capture system attached to the tailpipe that safely removes the carbon and stores it in some stable form as you drive down the road, why haven’t they? Where’s the working prototype?

Here’s the background from an article that promotes carbon capture and sequestration, written by a very prominent Harvard geochemist: Daniel P. Schrag, et al. Preparing to Capture Carbon, Science 315, 812 (2007):

“In 2003, President Bush announced a commitment to FutureGen, a DOE project to build a zero-emission coal gasification plant that would capture and store all the CO2 it produced.

FutureGen is an exciting step forward, but a single coal gasification plant that demonstrates carbon sequestration is unlikely to convince the world that carbon sequestration is the right strategy to reduce CO2 emissions. Moreover, a power plant operated by the government may fail to convince power companies that the costs of sequestration are well determined. . .

Luckily, FutureGen has competitors. British Petroleum (BP), in cooperation with General Electric, plans to build two electricity-generating plants, one in Scotland and one in California, that would sequester CO2 with enhanced oil recovery. Xcel Energy has also made a commitment to build a coal gasification plant with sequestration. And more projects may soon be announced as companies begin to view legislation controlling CO2 emissions as a political inevitability.

So, what are the problems?

One is that a lot of this work is being done within the murky “public-private sector”, making it very hard for someone to independently evaluate it. However, since FutureGen was supposed to be state-of-the-art in terms of carbon capture and zero-emissions coal power, the flagship example, it’s worth looking at.

The problem is the capture end. In the case of biomass, the carbon came out of the atmosphere when the plant grew, and is returned when the biomass is burned. For coal, the stream of combustion products has to be captured and sequestered – and coal is generally loaded up with sulfur, arsenic, mercury and other elements that have to be removed and disposed of as well. There are no such problems with biomass, and no need for carbon capture – just a limited supply.

FutureGen intended to capture the carbon produced from coal gasification before the syngas mixture was burned (syngas is CO +H2). This was intended to produce a pure, easy-to-capture stream of carbon monoxide…a deadly poison – and a pure stream of hydrogen for fuel use.

It’s actually hard to find the details of what went wrong with FutureGen and led to the project’s cancellation. There are no published papers on it, and apparently no independent peer review either. Here’s one blurb: U.S. Dumps FutureGen Project, Fri Mar 2008.

Now, carbon capture proponents have fallen back on promoting capture after the coal gas is burned, also in IGCC plants. The CO2 is more dilute, so more energy will have to be used to remove it. No one is going to outfit existing coal-fired power plants with carbon capture systems, because that would suck up almost all the power produced by the coal plant – they are proposing to build more IGCC carbon-capture plants, when they have yet to demonstrate that the technology can work at anything near the proposed scale- 20 lbs of coal per person per day in U.S., adding up to a billion tons of coal per year, resulting in the need to store about 3 billion tons of CO2 – per year – in the U.S. alone. The notion is ridiculous.

Finally, we already have the means to replace all coal-fired power stations using wind(Wind power leads British push to sustainability) and solar (Solar Thermal Power Could Supply Over 90 percent Of US Grid), and energy storage technologies (New NaS battery packs powerful punch). Biofuels and nuclear can also be carbon-neutral options, but on a case-by-case basis. That’s where any new investment should go.

Realistically, we should ban all new coal-fired power plant construction, and as they existing ones become decrepit, they should be replaced with clean energy systems.

David B. Benson:

April 3rd, 2008 at 4:37 PM

Kiashu (136) wrote “CH4 generated from CO2 injections into coal seams will be burned, releasing more CO2, so this may not actually be a net sequestering of carbon; no calculations have been made public”. Test results are on the web: coal seams naturally have some methane chemically bound to the coal. The introduced CO2 displaces the methane, as it binds tighter. The ratio is between 2 and 3 molecules of CO2 for every molecule of CH4 displaced. Since the expressed methane can be captured for introduction into the natural gas network, the result is a net gain of between one and two.

As best I can make out, nobody is pushing this strategy. Sequestration of CO2 in deep saline formations offers, it appears, a similar chemical affinity and without any methane being expressed (it is currently thought).

DBrown:

April 3rd, 2008 at 5:15 PM

Phillip Shaw,
Your claim that CO2 can be captured from the atmosphere in a cost effective (energy) manner by simple compression is not possible. I will not waste my time to give you the details but here is a start: PV = nRT (the standard gas equation). Learn some basic physics and please figure out the pressure for your self in order to liquefy CO2 and determine how much CO2 (mg) you will get per cubic liter of air (CO2 @ 0.038%) and a PV chart.
You simply embarrass yourself when you attempt to talk like you know something when you do not even offer the simplest thermodynamic calculation – as for getting ‘waste’ water, please, the amount obtained is only what’s already in the atmosphere (read about humidity and how much water is generally present in a desert atmosphere on a normal day) and that quantity will never be significant enough to provide water for a desert facility in a cost effective manner to grown large number of plants – it would be far easier to pump ground water.
Your idea that you can capture a significant amount of energy by re-expanding the gas is middle school reasoning and you are showing that you do not understand even science on that level – the Carnot cycle can be used to determine the efficiency of any heat based system and doing what you claim is nonsense – high temperature stream turbines (i.e. coal power plants operating at the temperature difference of over a 1000 C can, maybe reach a 38% conversion efficiency. And you think a 200 C or so differential is efficient enough to make a significant contribution to a compression process for energy recovery? Your ignorance is extreme and you need to learn some physical chemistry before you make any more technical claims about a process being ‘economical’.

Phil Scadden:

April 3rd, 2008 at 5:20 PM

“As best I can make out, nobody is pushing this strategy. Sequestration of CO2 in deep saline formations offers, it appears, a similar chemical affinity and without any methane being expressed (it is currently thought).”

Lots of people looking at (including us). While the gains arent as high the CH4 recovery is a partial cost offset at well.

NZ govt at moment has a moratorium on any state-owned company building any new thermal generation unless there is CO2 sequestered or offset so a lot of interest. The issue though is that the size of reservoirs are small compared to deleted gas reservoirs.

Jim Galasyn:

April 3rd, 2008 at 5:42 PM

Re 137: I, for one, welcome our new chemist overlords. I’d like to remind them that as a trusted TV personality, I can be helpful in rounding up others to toil in their underground carbon mines.

Erich J. Knight:

April 3rd, 2008 at 8:32 PM

The co-benefits of Biochar must also be considered beyond Bio-fuel gains; 3X fertility,17% less water use, Massive fungi (Glomalin) and wee-beastie microbes to worms, are sequestered carbon adding to that of the Biochar which in Terra Preta soils has C13 tested to 7000 years.

“we’ve found with some of the biochars in that we’ve had very, very significant reductions in nitrous oxide emissions from the soil; between five- and ten-fold reductions in nitrous oxide emissions.”

Erich

Robert:

April 3rd, 2008 at 8:50 PM

Re 126: You really don’t understand CO2 capture. Several points:

1. CO2 capture is currently practiced at the Dakota Gasification Company SNG (substitute natural gas) plant in North Dakota. CO2 is recovered and pipelined I believe over 100 miles to Wyoming for use in an oil-field miscible flood. So don’t say it hasn’t been proven.

2. The parasitic power consumption and loss of energy due shifting CO and H20 to CO2 and H2 is 84 MW for a 640 MW IGCC plant using GE’s gasifier design, or 13% (see NETL’s website http://www.netl.doe.gov/energy-analyses/baseline_studies.html) This case assumes 90% CO2 capture, and includes compression costs (2200 psig) to transport the CO2 50 miles by pipeline.

3. Oil companies do not get the majority of their CO2 from industrial plants, but from natural CO2-producing formations, such as Sheep mountain in Colorado. That CO2 is pipelined to the permian basin in Texas for a miscible flood, and they’ve been doing it for decades.

Re 135: You say that futuregen would capture CO, a poisonous gas. Wrong, it would shift CO to CO2 and H2, and capture the CO2 while the shifted synthesis gas is at very high pressure, about 450 psig or so. This helps to minimize the size of the absorber, and reduces compression costs of the CO2 after recovery from the stripper.

There is no problem with the feasibility of futuregen; the issue is economics. Until carbon capture is mandated, no one is going to waste their money on it, pure and simple. Nothing murky or sinister….

I have over 30 years in the chemical industry, and have been investigating gasification for about four years for my company. It is a technology practiced widely to produce chemicals; e.g., Eastman uses it in their Tennessee plant to make acetic acid, and derivatives such as tylenol. Pain relief from coal!

The problem, once again, is that until there is a mandate, power plants will not move forward with this technology.

Robert:

April 3rd, 2008 at 8:58 PM

I forgot to mention once again the potential for gasification with CCS using biomass. Note that Nuon, a power company in the Netherlands, practices this today, using I believe up to 15% biomass mixed with coal. There is no reason this percentage could not be higher. This makes so much more sense then air capture of CO2. See my earlie post #76….

April 3rd, 2008 at 10:24 PM

Nope, still didn’t work. I think I’ve figured out what did it, the “less than” sign is used in html, so… anyway, here’s the corrected quote, please delete my last post.

“A key comparison illustrates the daunting scale of the challenge. In 2005 worldwide CO2 emissions amounted to nearly 28 Gt; even if were to set out only a modest goal of sequestering just 10% of this volume we would have to put away annually about 6 Gm3 (assuming that all of the gas is compressed at least to its critical point where its density is 0.47 g/mL). The current extraction of crude oil (nearly 4 Gt in 2005) translates to less than 5 Gm3. Sequestering a mere 1/10 of today’s global CO2 emissions (less than 3 Gt CO2) would thus call for putting in place an industry that would have to force underground every year the volume of compressed gas larger than or (with higher compression) equal to the volume of crude oil extracted globally by petroleum industry whose infrastructures and capacities have been put in place over a century of development. Needless to say, such a technical feat could not be accomplished within a single generation.”

Phillip Shaw:

April 3rd, 2008 at 10:56 PM

Re 137 dbrown:

First let me say that the tone of your comment seemed a bit cranky . . . perhaps you should consider switching to decaf. Second, this is not the forum for flame wars.

And the funny thing is, you’re wrong. ASUs are not a pipedream, they are commercially available today in a range of capacities. If you google “air separation unit” you should get more than 78,000 hits. Add “carbon capture” to your search terms and you’ll still get a thousand or so hits. Granted, most of the proposed carbon capture approaches that use ASUs use them to produce purified O2, but the principle is the same.

You are correct that a tremendous amount of air would have to be processed to capture a meaningful amount of CO2. Nobody has claimed otherwise, so what’s your point? You’ve correctly pointed out that desert air contains little moisture but, again, nobody has claimed otherwise, so what’s your point? In many desert areas there is little or no groundwater to use, and what groundwater is available is often overcommitted to agricultural and municipal users. So however much water solar powered ASUs produced, it would be water available for growing biomass.

The concept I put forward is just that – a concept. One which may, or may not, be practical and feasible. I can’t answer that question. It was put forward simply to stimulate discussion and alternative ways of looking at the problem of carbon capture. I believe that is what this thread is intended for. I really don’t see how your rudeness adds anything for anyone but yourself.

And, no, I didn’t embarrass myself because I didn’t pretend to be more than I am. You, on the other hand, have much to be chagrined about.

April 4th, 2008 at 3:36 AM

Re #126:

Martin at comment #117 writes that “BTW you are accusing a large number of honest, competent and hard working scientists and technologists of being involved in “a crock”.”

That’s the appeal to authority logical fallacy.

No it is not. It is just what it appears to be, taking exception to insulting language.

I see that you are now starting to address the substance of the matter. Why didn’t you start with that?

– CCS has not been fully successfully trialled anywhere.

Precisely. Any solution to the AGW problem will be a portfolio of “wedges”. Shouldn’t we give this one a chance too? (I used to be skeptical about CCS like you even up till recently, and you may still be right, but don’t you want to find out?)

Chris Squire [UK]:

April 4th, 2008 at 4:21 AM

Use & l t; to get HTML to display ‘less than’. ‘As computer programmers might expect, “nop” means “no operation”, ie don’t do anything. It’s occasionally useful in programming, but I don’t know why they invented it for HTML; nevertheless it comes in handy for this situation. E.g. http://widget.com/xyz.jpg ‘

pete best:

April 4th, 2008 at 4:31 AM

There are a lot of opinions and assumptions in these posts on CCS, Thorium nuclear plants, Algae CCS and Algae biofuels etc but also some very good posts and what look like good facts on CCS and Co2 sequestration in general.

The porblem is that some think it feasible and point to existing plants that already CCS for enhanced oil recovery rather than burial under the ground. My issue us that each power plant is going to be different in regards to where CO2 will be pumped, the costs, and even the feasibility. Reading all of these posts just makes me more and more confused.

Some people obviously know something about thermodynamics and spent hot gases, about the energy requirements of Co2 capture from the air or from exhaust or pre exhaust gases but there is no consensus here it would seem.

Thorium power plants are viable but from what I have read not economically preferred due to Uranium being the preferred fuel as it is subsidised and there is a lot of vested interest in it.

It looks like CCS is viable but FutureGen has been cancelled and as Ike points out in post #135 there is little actual technical data on why it has been cancelled but the costs seem to indicate something of its demise. The question is: enhanced oil recovery is one way of using spent Co2 gases and seems to demonstate that you can take a very hot gas and cool it, sequester the CO2 and use it to recover more oil from depleting fields. Does not this prove the viability of CCS at all?

getting very worried now about it all.

pete best:

April 4th, 2008 at 4:36 AM

Re #142 qand #76. Do you have any particular reason for not thinking that 000’s of scientists using the same methods and analyses as you do in your field of endeavour have got it completely wrong or are you of the opinion/knowledge that as yet the jury is still out or that they do as yet not have enough data to make the statements that the IPCC and GISS etc do?

After all climate science is a mixture of physics, chemistry, biology, geology, astrophysics etc and hence is hightly quantitative and detailed.

I would like an explanation of your position if you can find the time to reply?

pete best:

April 4th, 2008 at 4:51 AM

Re #141, Robert, a great post and one that points to the fact that if all you have posted is true (hard to judge from an laymans perspective you understand but I have no reason to doubt you all the same) that it is economics that prevent CCS from becomming a reality and not any technical obstacles to be fair.

is that a fair assessment of the situation. It is politically and economically undesireable at the present time due to the costs of implementation? If this is the case and it is eventually actively implemented, how long before a fully working CCS coal fired power plant could be tested. A decade ?

Nick Gotts:

April 4th, 2008 at 5:12 AM

Re #135 Ike, don’t argue it with me, I’m no expert. Argue it with the IPCC: see their Special Report of Working Group III on CCS. I’m all in favour of renewables, energy efficiency and demand reduction; my main reason for supporting CCS research is that I just can’t see China and India leaving their cheap and abundant coal in the ground. I disagree that “the car example is a good one”, since to my knowledge, no-one has seriously suggested CCS on such a tiny scale. Scale makes a difference, you know. My original point was simply that you were posting rubbish because you hadn’t bothered to differentiate between the subject of the post – air capture – and CCS from power stations.

Figure 1 in 07-09.1999.07Velbel.pdf says Mg2SiO4 weathers at the rate of 10^(-12.1) moles per square-centimetre-second. Fe2SiO4, -10.5. Don’t know Mg2SiO4’s density, but if it’s 3 g/mL, there are 0.02 mol/mL and figure 1 says it takes 27 billion seconds to weather forsterite one centimetre. For fayalite of the same molar concentration, 0.67 billion seconds.

Suppose we have got the forsterite to 80 percent pass through a 100-micron screen by spending 25 kWh(e) per tonne, 12.7 kJ/mol, crushing it. Now weathering has to eat 0.005 cm from both sides to get to the middle, and that takes 135 Ms. Four years.

it was plausible. I have been chastised for gathering that it was fact from chitchat surrounding the paper that revealed it rather than the paper itself. Here is that paper’s abstract:

We have documented active sequestration of atmospheric carbon dioxide (CO2) in chrysotile mine tailings at Clinton Creek, Yukon and Cassiar, British Columbia. Hydrated magnesium carbonate minerals develop in mine tailings as a natural consequence of the weathering process within the residues. Magnesium, leached from minerals, reacts with dissolved CO2 in rainwater, precipitating carbonates at the surface of tailings upon evaporation of pore fluids. Increased reaction rates are observed in the tailings environment due to fine grainsize resulting from mineral processing. Mine tailings may therefore represent the optimal environment in which to pursue mineral sequestration. X-ray powder-diffraction studies demonstrate that CO2 is crystallographically bound within the hydrated magnesium carbonate minerals nesquehonite, dypingite, hydromagnesite, and lansfordite. Quantitative phase analysis with X-ray powder-diffraction is used to determine the modal abundance of hydrated magnesium carbonates in mine tailings. An atmospheric source of CO2 is confirmed with stable and radiogenic carbon isotope techniques. Serpentine and olivine-rich tailings are produced by many types of mining, including nickel, diamond, platinum, and chrysotile. The global scale of these mining activities has a sequestration capacity on the order of 100 million tonnes of carbon per year. Widespread implementation of mineral sequestration in mine tailings has the potential to render large mining operations greenhouse gas-neutral and significantly reduce CO2 emissions on a global scale.

Patrick:

April 4th, 2008 at 11:00 AM

The one source of energy that is done more to reduce emissions from power generation than any other source is … nuclear.

Thousands of operation-years of experience in the US and other advanced countries have proven it to be reliable, safe, environmentally sound and economical. All those adjectives can be argued but in all cases the alternatives are worse. (To rebut the standard concerns; Chernobyl was Stalin-era technology, and abysmal USSR operating standards, different category; nuclear ‘waste’ is used fuel that can be safely stored and then eventually reused.)

Carbon sequestration and “50 SIMPLE THINGS YOU CAN DO TO SAVE THE EARTH” are going to be indirect and inneffective. Direct and effective would be non-fossil fuel energy sources; we just need nuclear power to be our baseload power generation source. If nuclear became 75% of our electricity generation (baseload), and if wind, renewables etc. complimented it for another 20%, and if transportation energy was displaced partially by electricity via plug-in hybrids … then USA could cut CO2 emissions by almost 2/3rds. And do it without huge CO2 emission mitigation costs.

We should stop pretending there is no solution or the solution would be hugely expensive. We could provide subsidies that cost less than our ethanol subsidies, and get to a France-level adoption of nuclear (70%) in the next 30 years. No big deal.

The #1 impediment to solving the GHG emissions problem is the money we waste on non-economical solutions (hydrogen cars, carbon sequestration, ethanol, etc.).
If FutureGen can be done economically, great, but we wasted $20 billion on SynFuels in the 1970s and 1980s, and this has the feel of another great engineering idea that is simply not economical.

David B. Benson:

April 4th, 2008 at 12:52 PM

Phil Scadden (138)— Pleased to read of it. One possibility for additional CO2 sequestration is to use biomass to produce carbonaceous solids such as biochar or biocoal. Bury these materials in an abandoned mine or a carbon landfill. Then squirt in the CO2.

Ray Ladbury:

April 4th, 2008 at 1:34 PM

G.R.L. Cowan, I wasn’t saying that weathering did not happen w/o concentration, but rather that it would be too slow to make a meaningful contribution. I think your calculations pretty much show that. It is all about exposing surface area to gas. That takes energy, no matter how you slice (or pulverize) it. There may also be competing reactions, particularly if the forsterite is not pure Mg end member. That weathering will happen is beyond doubt. That it will not happen on a timescale meaningful to human survival without significant intevention on our part is also pretty much certain.

Ray Ladbury:

April 4th, 2008 at 1:41 PM

Patrick, I don’t think we can prejudge the outcome at this point. We may have to resort to all strategies available to us to circumvent this threat. To speak as if the nuclear waste storage problem would be completely solved by fuel recycling is disingenuous. Recycling leaves lots of nasty isotopes that still need to be dealt with. Proliferation is not a trivial concern either. Personally, I think these problems can be dealt with and think nuclear power may be part of the solution, but it isn’t a solved problem.
And yes, our politicians tend to lavish money on solutions that garner votes rather than decrease carbon emissions, but that is an issue for an educated electorate. It may be that inefficiency in government expenditures is the price we need to pay so that real strategies are pursued in addition to the boondoggles.

Kevin Leahy:

April 4th, 2008 at 1:47 PM

Re 149 & questions re CCS. It is genearally accepted in the industry that CCS is likely to work. If you talk to oil folks, they tend to see little risk given their experience with EOR. The individual who claims all previous experience shows these do not work is bucking the published lit and field experience. Re why it isn’t happening on a large scale — yes, it is the economics. Until there is a price on CO2 in excess of $30 to $40/ton, CCS off of an IGCC is not competitive with a conventional, emitting coal plant. CCS off a conventional plant is unlikely to be competitive except for a few very new facilities in particular electricity markets (most likely the US Midwest).

The tech has not been demonstrated yet at large scale. Efforts are underway to try to gain govt support in partnership with industry to do the deomonstrations. The industry believes it will take 10 years to get a plant up and running and another few years to gain full understanding of how the large scale injection behaves at depth. Once we KNOW it works, we will need to build hundreds of these facilities — the MOST optimistic projection is that all existing coal in the US can be retired and replaced with this new tech by 2040 to 2050.

Yes, it will be expensive, but it is the least expensive option, along with expansion of nuclear for hiting a target of 60 to 80% reductions by 2050. Check out EPRI.COM for presentations re their analysis.

Those who claim otherwise lack an understanding of the scale of the energy system and amount of emissions involved.

Re Futuregen. It was cancelled because of a change in thinking at DOE, moving from the idea of supporting a single large plant/test site, to providing the incremental funds to perform test at several smaller sites in partnership with single firms. It was felt you’d be able to learn more/conduct more specific research through the latter approach. The project was not cancelled because it doesn’t work or was deemed a failure.

Re the original idea of removing CO2 from air, again, one of the least costly alternatives possibilities so far is algae used as feedstock in IGCC, generate power and capture and geologically store the CO2. The CO2, just as in the process using coal, is captured before combustion, is concentrated and already at very high pressure — the remaining H2 is then combusted.

DBrown:

April 4th, 2008 at 4:48 PM

That ‘perhaps you should consider switching to decaf.’
Yes, I relapsed.

and ‘ Second, this is not the forum for flame wars.’
Correct – you are trying to address a serious issue and should get a professional response.

I will not try and address all the issues you raised but one thing I want to say up front: The issue of ASU’s or for any process made here is not whether they work and I have not once stated that any process discussed here can not work – only that some are not good approaches in terms of money/energy relative to the idea of removing CO2 from the atmosphere. No matter how you approach that issue, entropy is working against you and calculating real energy costs is critical – especially when you make strong claims relative to the process; otherwise, you end up with the monster boondoggles like corn based ethanol that is driving world food prices up, not addressing real US energy issues in a wise manner and worse, may lead to terrible hardship (read: deaths) for many people who did nothing to deserve such a tragedy – so be careful about claims.

The main issue is that many people here are making claims about approaches with little and in some cases, no proof. This is not appropriate even in a blog – if you claim something, back it up with facts; otherwise, it is just opinion and needs to be qualified as such.
No matter the approach, every thing is about energy cost and any process that consumes available funding (very limited) must justify its methodology relative to payoff and efficiency or it is just more ‘waste CO2′ in the atmosphere.

April 4th, 2008 at 5:40 PM

I wasn’t saying that weathering did not happen w/o concentration, but rather that it would be too slow to make a meaningful contribution. I think your calculations pretty much show that. It is all about exposing surface area to gas. That takes energy, no matter how you slice (or pulverize) it. There may also be competing reactions, particularly if the forsterite is not pure Mg end member. That weathering will happen is beyond doubt. That it will not happen on a timescale meaningful to human survival without significant intevention on our part is also pretty much certain.

If the olivine is not pure forsterite, more of it must be comminuted, but we can get away with particles that are less minute, because if much of the iron member, fayalite, is present, it much speeds up weathering.

Your paragraph changes directions halfway through. Too slow to make a meaningful contribution — bad news — or too slow to do so without significant intervention on our part — neutral-to-good news?

I agree with the direction taken by the paragraph’s second half. I understated the pulverization energy aspect of the “significant intervention” we should do by calling it 6 kJ/(mol CO2) without reiterating that these are kilojoules of electricity. Of primary energy, ~20 kJ/(mol CO2).

Still a good deal compared to the 350-ish numbers that were being claimed for some other processes that, if those numbers are true, are ridiculous.

Count Iblis:

April 4th, 2008 at 7:09 PM

Why not switch to nuclear energy? The volume of nuclear waste you need to store per joule of produced energy is much smaller than the volume of CO2 that has to be stored.

Ray Ladbury:

April 4th, 2008 at 8:23 PM

Count Iblis, As someone who favors greater use of nuclear power to limit future climate change I still have to protest–stored CO2 presents little risk for creating WMD, while nuclear waste does. We risk a backlash if we do not admit the difficulties nuclear power faces. They are not inconsiderable and they are not solved. I believe they can be solved, but not without considerable effort and probably some residual risk. Handwaving arguments should not carry the debate wrt something this important.

April 4th, 2008 at 9:37 PM

Why not switch to nuclear energy? The volume of nuclear waste you need to store per joule of produced energy is much smaller than the volume of CO2 that has to be stored.

A total switch tomorrow morning would still leave ~200 billion tonnes of legacy CO2 in the air. It will be pleasant to ease the [CO2] back to where it was, and as I’ve been saying, a few hundred gigatonnes doesn’t make much of a dust layer if it’s innocuous dust (as it would be) dispersed over large areas of the planet’s surface — including sea surface.

I can’t fault nuclear energy on the harmlessness-in-practice its leavings have shown, but lots of people can; or anyway, fault it, not exactly on that, but on what they seem to believe is a likely lack of future harmlessness.

This, I think, reflects the fact that when governments allow their citizens to switch to nuclear energy, governments lose money. The recent price of a uranium-tonne-equivalent in natural gas was $5.2 million, inclusive of royalties but not of special end-user taxes. A tonne of the real thing costs less than $0.2 million, and at that sort of price has been being prospected at ten times the rate of use.

So if you want to make the tax man your friend by pretending to be irrational, there are several nuclear-energy-related options. You can pretend to believe nuclear powerplant waste will be very different, no longer entirely harmless to all its neighbours, in the future; or that nuclear weapon proliferators will start using materials from, or putatively destined for, power reactors, despite in all known history having always chosen easier, more effective ways. Other such routines will soon be on display.

They all serve to help governments slow the switch to nuclear by diverting attention away from the lucrativeness to governments of such delay. That lucrativeness is why it takes such an amazingly long time to get permits to build a nuclear power plant. Nuclear developers aren’t going to completely roll over City Hall before this year is out. If they could, nuclear plants would still take time to build, and the very long paper chase will have institutional inertia.

So a lot of legacy-CO2-to-be is still sitting underground as CH4, and a lot of innocents are going to be blown up by it, or poisoned by it when it has lost its hydrogens and gained only half its usual pair of oxygens. There are forms to fill out, and new, shorter forms can’t be brought on stream overnight. So we won’t be able to prevent that, nor to resurrect those people, but in due time we will be able, not too expensively, to take down the CO2.

Jim Eaton:

April 5th, 2008 at 2:44 AM

It’s really hard to see what events are necessary to awaken Americans to realize that lifestyle changes are mandatory to reduce CO2 impacts. As I returned from the Bay Area to Davis last week, I drove a safe and sane 70 MPH, although (except for a few semi-trailer trucks) I was the slowest passenger car on the road. I watched SUV after SUV, one driver to a two-ton chunk of steel, blew by me at speeds up to 80 MPH or more.

In the (relatively affluent) neighborhood I live, Village Homes, nearly a quarter of the residents have installed photovoltaic systems on their roofs. And although many of them do what they can to reduce energy consumption (walk or take the bus to work, buy local produce, and compost everything they can), their carbon footprint is still relatively high. I sincerely appreciate all their efforts, but it still is a far cry from being carbon neutral. And this is from a community that is able to afford to pay for green alternatives.

But the nuclear option raised on this blog gives me serious concern. Although I greatly respect the contributions of Ray Ladbury, I just can’t accept the idea that to deal with anticipated energy demands we must embrace nuclear power. It reeks of robbing Peter to pay Paul. We take an energy alternative (not without the carbon emissions of building the facility and mining the fuel), use it for a few decades, then plow fossil fuels back into sequestering dangerous radioactive spent fuel and power plant materials for many thousands of years. Not to mention the weapons concerns of the dangerous waste.

What do I propose? Well, along with a great reduction of human propagation, I guess I do vote for renewable energy sources. Not they they all are benign (wind energy systems have become bird Cuisinarts in too many locations). But here in sunny California, I would ask that every new building be outfitted with photovoltaics and that there be a subsidy to retrofit all other buildings with solar panels.

But from my freeway experience, I think of the oil crises of the 1970s. Set the national speed limit at 55 mph. And enforce it. On my last trip to Australia, I was astounded to see that most folks obey the speed limit. When you enter towns, there often is a notice of the presence of speed cameras. Even in the countryside, mobile speed cameras may be present. And if you drive over the speed limit, the owner of the car receives a citation. So I did not see many folks exceeding the speed limit. If you exceed the limit and are captured by a camera, you will pay.

I know it is an American tradition it ignore traffic laws (have you watched a young person at a stop sign recently?) But we are faced with a crises that demands desperate actions. Rather than trying to accommodate anticipated energy demands in the future, we should be preparing our folks for the reality of the future. Conservation and renewables are the way to start. Other measures may prove necessary in the future.

pete best:

April 5th, 2008 at 4:36 AM

Re #156. Kevin, if what you say is true then I am afraid then CCS is not going to help us in our fight to combat 2C of warming which is looking less and less likely for eacy 7 to 8 billion tonnes we release per annum. It might help us in fighting >2C but the time scales you specify means retrofitting which seems even less likely politically and economically.

CCS is a green wash by the looks of it and should not be listed as a means of combating AGW until it is ready to fit to both existing and new coal fired power plants. until that time coal should stay in the ground as James Hansen is stating.

Nick Gotts:

April 5th, 2008 at 7:16 AM

Re #161 [G R L Cowan]

What an amazing load of hooey. In Europe at least, governments have mostly been promoting nuclear energy in the teeth of public resistance. Why is it so many nuclear advocates come out with this sort of rubbish?

Ray Ladbury:

April 5th, 2008 at 7:28 AM

Jim Eaton, I think my posts make it clear that I do not discount the difficulties of nuclear power. I just don’t think we can preclude or prejudge any option at this point if we want to acheive sustainability (economic, ecological and social), and sustainability is a prerequisite to the survival of civilization.

Jerry Toman:

April 5th, 2008 at 9:49 AM

Here is an alternative “cryongenic” carbon capture approach. I’m not saying it would be economic, or that it wouldn’t need testing or developmnent to minimize “solvent losses”, but should be way more efficient than starting with air containing only 400 ppm CO2.

Compress air in two stages to 10-15 bar. Use it to burn coal to CO2 in a “pressurized fluid-bed combustor” to generate steam, and during which process which some of the impurities can be adsorbed.

Cool combustion gases, pre-heating boiler feedwater in the process, and remove any water that condenses.

Next, pre-cool the high-pressure gases with offgas, after which they are expanded to about 1.5 bar. If this doesn’t produce temperatures cold enough to condense out solid CO2, wash the offgases with either a physical solvent or one that is combined with a chemical absorbent to increase capacity.

Use the CO2 lean off-gases to pre-cool the combustion gases before releasing to the atmopshere. Regenerate physical solvent with waste heat from the combustion process.

Of course, “partial combusion” variations of this theme are also possible.

DBrown:

April 5th, 2008 at 10:10 AM

Those saying nuclear power is a good solution, I was wondering which type of nuclear fission plant?
As for Europe, the French are using breeders and these can be terribly dangerous (see my post # 122; however, ignore the fool behind the curtain in post # 137).

I do not believe that nuclear power, except in the Canadian approach, is either safe or desirable. The old mantra “Keep it simple, stupid” should be printed on all nuclear engineering textbooks.

April 5th, 2008 at 12:19 PM

What an amazing load of hooey. In Europe at least, governments have mostly been promoting nuclear energy in the teeth of public resistance. Why is it so many nuclear advocates come out with this sort of rubbish?

To anyone who follows the money, it doesn’t look like hooey.

In Gotts’ version, the motivation of governments is obscure: they work against toothed public resistance in order to lose fossil fuel income. Governments. Who can figger’em, eh.

Well, perhaps this will help in figuring them: per Ghislenghien- or Piper-Alpha-style death, per similar death in the much more numerous small fossil fuel disasters, they get a few tens of millions of Euros in oil and gas revenue. If they work to create the appearance of public opposition to nuclear energy development, they can justify the continuation of those lucrative deaths as something the public is forcing them to accept.

April 5th, 2008 at 8:35 PM

As regards “… and then we all die.”, I think it’s worth noting that as the youngsters who are going to be the victims of “… and then we all die” approach voting age, the odds that enough of them will want to NOT die, and therefore vote different, increases.

China can’t keep doing what it’s doing — their cities are massively polluted and things ain’t getting better. Look for a Soviet-style collapse any year now.

Frank Zeman:

April 5th, 2008 at 10:36 PM

A few more comments. Kudos to those posters who are calling for civility. In topics like this, it is easy to get passionate.

There is the question of why should some money be invested in air capture at this stage. There are two real reasons. First money is being spent of hydrogen and electric vehicles when it is far from clear that they are the most cost effective solution. For starters the cost of the vehicles has to come down by at least one order of magnitude and they both require billion dollar infrastructure. Secondly, whatever the cost of air capture, and it is initially expected to be much higher than conventional CCS, the final cost sets an upper limit on the cost of climate risk mitigation. It removes some uncertainty about the cost of solving the climate problem. This information may prove to be useful.

Another point is that when considering any technology it is important to view them all as transient. We do not know what technologies will be around in 2050. We research things that look promising and implement things that have an immediate effect. Like efficiency, CCS would have the immediate effect of reducing CO2 emissions to the atmosphere. This does not mean that CCS will be used in 50 years, the conventional lifetime of an industrial facility.

Mineral sequestration has the challenges of cost and kinetics. The absorption does indeed occur naturally but at a very slow rate. This is improved by attrition grinding and heat treatment, which consume too much energy.

The ASU question can only be answered with a detailed design as the operating temperature of the facility rises from -180oC to -60oC. We can get started by recalling that a conventional ASU (producing O2) consumes 20 kJe per mol O2 or 10.5 MJe per mol CO2, as O2 is 20% and CO2 is 0.04%. The remaining question is the relation between operating temperature and energy consumption. Assuming it’s linear would result in one third less or 3 MJe, if quadratic then 1 MJe. Then you need to consider the primary energy used to generate the electricity.

Then a stab at the specific list of questions presented earlier (126):
1) the energy required to produce liquid CO2 is expected to consume 21% (see IPCC SR CCS) maybe more but 33% would be an upper limit not minimum.
2) very good question: if we only use CCS then we build more plants. A better solution would be to save that 20% using efficiency ideas proposed by Amory Lovins and others.
3) CCS from a power plant has not been attempted. There are three large CCS projects (Weyburn, Sleipner and In Salah) that are based on pressure swing absorption (easier and cheaper than thermal swing necessary at power plants). Without market signals or regulations it is unlikely that any will start.
4) You do not reference a specific operation. The midland Texas CO2 injection projects derive there CO2 from natural deposits in Colorado. The gas is pipelined down proving the transport technology.
Weyburn uses gasification CO2, which is also pressure swing absorption. Thermal swing absorption is done at refineries, which is were soda plants get their CO2.
5) Again, you do not reference sites. No leakage has been measured at the three projects mentioned above and they are really looking. The only leakage site I’m aware of is Mammoth California, a natural occurrence. Another famous case is Lake Nyos in Africa, again natural. It integrity of the storage site depends on the cap rock and a suitable one must be verified. Oil reservoirs have been held in place for millions of years so it should be possible.
6) methane leakage from all coal recovery projects is serious. As mentioned in another post, the USGS expects more CO2 to stay down than methane come up. Also burning the methane results in less emissions than burning coal.
7) Air Capture is aimed at vehicles and small sources, that is the point of the article. Some agricultural greenhouse gases can be reduce by altered irrigation etc but it’s hard. Emissions from meat production are even bigger to my knowledge.

Thanks for all the good comments.

April 6th, 2008 at 10:16 AM

Re 170: For starters the cost of the vehicles has to come down by at least one order of magnitude and they both require billion dollar infrastructure.

For electric vehicles this is patently false. I have to get rid of my gas guzzling V8 sports car (but only for a few years — I’ll buy another after the teenager departs the nest ;) ) and will likely replace it with a two-seater electric commuter that I’m expecting to run me about $13,000. It will plug into my wall in the garage. I may have to run an extra outlet to the other side of the garage, but I know how to add outlets to walls for less than a billion dollars.

Here’s the biggest problem — people are so brainwashed by the nay-sayers that they are incapable of action. That doesn’t cost a billion dollars to overcome.

Steve Albers:

April 6th, 2008 at 10:36 AM

Here is the link with biochar interviews that should work better than in the earlier post #71.

As another wedge I’m also hopeful about fusion power – where perhaps funding should be increased.

Nick Gotts:

April 6th, 2008 at 10:53 AM

Re # [G R L Cowan]

“If they work to create the appearance of public opposition to nuclear energy development, they can justify the continuation of those lucrative deaths as something the public is forcing them to accept.”
Repeated hooey is still hooey. How about some actual evidence of
governments doing this – for example, funding anti-nuclear organisations? Or is it a huge secret conspiracy that only you have managed to penetrate?

April 6th, 2008 at 1:51 PM

“If they work to create the appearance of public opposition to nuclear energy development, they can justify the continuation of those lucrative deaths as something the public is forcing them to accept.”
Repeated hooey is still hooey. How about some actual evidence of governments doing this – for example, funding anti-nuclear organisations? Or is it a huge secret conspiracy that only you have managed to penetrate?

If a secret were impenetrable to everyone but me, that would suggest but not prove that I was a nut and the secret was not real. However, the same commentator a day earlier said, “so many nuclear advocates come out with this sort of rubbish”, emphasis mine.

A government that sought to create the appearance of public antinuclearism and was not confident that its public would play along might stage a referendum in which voters were not allowed to approve of nuclear energy, instead being given only various choices on how fast to phase it out. An instance of this behaviour —

… Voters were asked to pick one of three ‘lines’. But by this time all three ‘lines’ had formulated policies calling for the eventual phase-out of nuclear power …

In the comments Frank Zeman says,

Mineral sequestration has the challenges of cost and kinetics. The absorption does indeed occur naturally but at a very slow rate. This is improved by attrition grinding and heat treatment, which consume too much energy.

The evidence I introduced might seem to indicate the energy consumed by grinding, aka pulverization, aka comminution, was, at ~20 kJ/(mol CO2), not excessive, and heat treatment unnecessary, but that is inconsistent with the axiom he ends his initial posting with:

It is not any kind of panacea though.

Jerry Toman:

April 6th, 2008 at 6:38 PM

What I don’t understand is the willingness of people to advocate the spending of tens, if not hundreds of billions of dollars to develop technologies that have little chance of succeeding, instead of going after the “low-hanging fruit”.

Expressed in terms of the original intent of the posting, which suggests the use air capture to remove CO2 from the air in compensation for lingering CO2 emissions that would be difficult or impossible to control, such as those emitted from highly distributed or mobile sources, a lot of proven and likely much cheaper possibilities remain to be examined.

Let’s take the CO2 emitted from consumption of home heating oil as a first example. This system has almost double the carbon footprint of natural gas for the amount of heating actually delivered. First, these homes should be preferentially targeted for increased insulation and weatherization. Next, the larger, newer ones should be required to switch to heat pumps, ground based or otherwise, in which case the CO2 emitted would be reduced by a factor of two or more if the fuel used in the power plant were heating oil, or even 1.4 if it were to be coal. In this case the heating oil could be diverted back into the diesel pool (after hydrotreating) enhancing what is otherwise a fuel in short supply. In this case, we would only be replacing what would disappear naturally via “Peak Oil”

For new construction, in most places, most of the heating requirements could be supplied by solar energy (Google Drake, Albera, solar). In any event the CO2 would be emitted from a central location, where it could be captured more economically, should a location for its ultimate disposal be found.

For large mobile sources, such as that produced by diesel locomotives, it might in fact be possible to use a couple of tank cars to carry amine solutions that would be loaded up with CO2 during the trip, and discharged for regeneration at central facilites, such as a coal mine where the CO2 could be injected into unminable seams. This might remove perhaps 50% of the CO2 emissions from these sources.

But this is still small potatos. A cheap, plentiful, reliable, carbon-free source of electricity could solve practically all our CO2 emissions problems. While I contend the development of the AVE would be a “slam-dunk” in achieving this goal, I can understand why most of the readers, for whatever reason, might not (yet) see it that way. As opposed to most of the ideas put forth here, however, this uncertainty can be resolved by a mere $50 million (or less) investment to devlop a final design and build one at an ideal location. If it works, game over. If it doesn’t work, at least I will be shut-up once and forever on this subject and you can all go forward with your more exotic and capital-intensive solutions, which will take years if not decades to develop.

I ask all of you, including Frank Zeman, what is wrong with this strategy?

May the AVE-Force be with you!

François Marchand:

April 6th, 2008 at 6:58 PM

According to the latest readings from the Mauna Loa Observatory, the increase in atmospheric CO2 appears to be slowing down. Two months do not constitute a trend, and -perhaps- so far, it might be only Mauna Loa, but does anyone have an idea about the carbon-capturing process at work? I know it can be dismissed as “weather”, but any trail?

April 6th, 2008 at 9:53 PM

Frank,

(#103) Thanks for taking a look. I would suggests then that molecular sieves make the most sense from an energy use standpoint. Absorption is slightly exothermic and may drive convective flow if properly arranged, or air motion from wind may be used for collection. I suspect that we will capture CO2 from the air to make liquid fuel sooner than we will do it to sequester the stuff so the energy input would need to be as low as possible to make the fuel economic should we run out of ways to use the process heat from the Fischer-Tropsch or Sabatier processes. The trade-off would be in cost of materials I think, but long lasting sieve material would seem to pay for itself through the energy saved since this seems substantial. Once we are making fuel from air capture (all the concentrated sources having been exploited) scale should be set to move into sequestration if it is really needed. I note that making liquid fuels from CO2 using renewable energy is about the only method that can approach current liquid fuel use, the Agrawal et al. (2007 PNAS 104 4828) H2CAR proposal notwithstanding. So, delays in electrification of transportation would likely push this sort of thing.

Again, thanks! I’ve been looking for energy estimates for other methods for a while now. I should note that the lowest energy method looks to me to be using the brightness temperature of the Antarctic night sky to freeze out CO2 using reflectors to isolate the air from the ground temperature, but this poses logisitcal difficulties. Klaus Lackner once mentioned to me that there has been a little work done on looking at stabilizing the bases of glaciers by freezing them colder though. There might be something there….

Nick Gotts:

April 7th, 2008 at 5:18 AM

Re #174 [Cowan] ““so many nuclear advocates come out with this sort of rubbish””. When I said that, I was thinking of Edward Greisch and others who insist that all opposition to nuclear power is paranoid – not exactly the same as your position, I concede, but similar in that it avoids the need to actually argue the issues. I’ll follow up your Patterson ref. and get back to you on that.

Nick Gotts:

April 7th, 2008 at 5:50 AM

Re #174 [Cowan] I’d agree that the Swedish 1980 referendum was flawed, but it’s hard to see that this could have anything to do with tax revenues from fossil fuels, since Sweden’s electricity is and was almost entirely produced either from nuclear or hydroelectric stations. More relevant is surely that the decision to hold a referendum was a reversal of a previous decision only the previous year; and that it followed closely the “Three Mile Island” accident – which temporarily made nuclear power far less popular in Sweden than it has generally been (Chernobyl had a similar effect). From what I can discover, the three alternatives in the referendum were each backed by one or more of the political parties represented in the Swedish Parliament; it appears that at that time, no such party was willing to take the political risk of being seen to be backing nuclear power. If you look at what has happened in Sweden since, few if any measures have been taken by any government to prepare for the phase-out of nuclear power, which is due by 2010. It clearly won’t happen. I conclude that if this is the best “evidence” you can come up with for the conspiracy you suggest, your belief in it is clearly not held on rational grounds.

April 7th, 2008 at 7:11 AM

Patrick posts:

[[The one source of energy that is done more to reduce emissions from power generation than any other source is … nuclear.]]

Yes, because other sources aren’t massively on-line yet. Apples and oranges. The best way to reduce GHG emission is to create new renewable power sources, not new nuclear plants. Photovoltaic, solar thermal, wind, geothermal, ocean thermal, tidal and biomass energy would be more helpful than nuclear, and a lot less dangerous. No country ever achieved nuclear proliferation because it had windmills.

Kevin Leahy:

April 7th, 2008 at 10:24 AM

Re 163 (pete), you are correct insofar as this plan, which is seen as the most optimistic so far, will likely only prevent >2 degree C change. Getting less than this is already in the rear view mirror unless people are convinced enough to make bigger changes which will need to include air capture (ah, back to the topic).

It is not however a retrofit question — unless you consider scrapping nearly all coal and replacing with CCS equipped plants retrofitting.

Re the assertion that this has to be done with all renewables and efficiency (R&E), I’ve yet to see a serious analysis that supports that that will provide enough energy unless you increase the cost of energy so much that people simply quit using it. The problem is made more complex by the fact that we have a couple billion people in developing countries that also will be trying to improve their standard of living from current levels of

David B. Benson:

April 7th, 2008 at 11:55 AM

François Marchand (176) — That dip is just for the Mauna Loa site. Notice that it has happened before, in 2004. Look further into the NOAA web pages to discover the average of all CO2 monitoring sites continues in a steady, rodust uptrend.

Kevin Leahy:

April 7th, 2008 at 2:46 PM

181 continued (my post was truncated)! Wanted to make sure the point is understood that the renewables/nuclear/CCS/energy efficiency is not in any case an “either/or” sort of issue as some would like to make it, rather the answer must be “all of the above.” This must be if we are to have any hope of getting emissions down enough to prevent the worst of GCC. To shrink the solution set is to invite an unraveling of support for an emissions reduction program because of escalating costs. And yes, I know all about the fact that “if we do nothing it will cost a lot more” but most people don’t see the bills that come due in 50 years, they see they bills they pay today. Wishful thinking to the contrary, it is in everyones’ interest for the policy to be cost effective.

Frank Zeman:

April 7th, 2008 at 7:49 PM

more comments

(171) Indeed commuter cars may cost as little as $13,000 (Smart fortwo) and I was referring to the Tesla Roadster currently at $90,000. The main reason is it gets 200 miles per charge as opposed to the 70 miles of the Smart, in rough numbers. The challenge is that hybrids get over 400 miles per gallon with a lot more interior volume. In addition, it takes 5 minutes at a gas station while Tesla gives it more than two hours. So while the single person commute might be handled by these cars, the whole range of services provided by gas vehicles is not. The question is what do we want cars for aside from commuting. I mentioned the infrastructure because the EV1 has special charging stations that cut the time down.

Aside from those points the electricity is not currently carbon free so that leaves two options. Implement CCS which requires infrastructure to transport and store the CO2 as well as capture. Alternatively convert the electricity generation fleet to renewables and nuclear, which would cost a lot of money, raise the price of electricity (in short term at least) and require upgrading of the grid to handle the intermittency. These are all going to take time and cost money, as will air capture.

(175) I agree, I think every idea in Amory Lovins “Factor 4″ should be implemented first if they make sense based on Lifecycle analysis. Some ideas, like increasing the gauge of copper wire I’m skeptical about. Needless to say, huge strides can be made using efficiency but even reducing electricity consumption by a factor 4 might be offset by global development and population growth.

The train with MEA idea is interesting Some thoughts would be that the mass of the train would increase the farther it travels. The scrubbing would also add backpressure to the engine. Finally I don’t think that diesel locomotives are a big player in the transportation sector. Every idea is worth looking at for back of the envelope.

What is AVE?

(175) You’re welcome. I don’t know much about the molecular sieve thing at all. I’ve read the H2CAR process but at this time I’m not keen on biomass solutions as the first priority should be feeding people.

(183) Couldn’t agree more. If you read Socolow’s Scientific American article about the wedges he mentions that air capture might be a wedge in the second half of the century. All solutions should be applied at this stage, including electric commuter cars. The lifetime of an industrial facility is 20-60 years so there’s time to change course and starting them all prevents lock-in.

My entire life is carbon negative. Click on the link by my name and you’ll see what it did to my electric bill.

Jerry Toman:

April 7th, 2008 at 11:18 PM

What is AVE–Atmospheric Vortex Engine

Scott Hawley:

April 8th, 2008 at 8:52 AM

This topic brings up a question that I have been pondering for some time. Why can’t we build a power plant that acts like a carbon sink. If a bio-fuel, like ethanol, power plant were designed and used CO2 capture and carbon sequestration would it not be carbon negative. The concept is simple, let nature concentrate atmospheric CO2 then burn it for power and sequester the CO2. The technology all exists but I have never read anything actually discussing the possibility.

David B. Benson:

April 8th, 2008 at 1:53 PM

Jerry Toman:

April 8th, 2008 at 2:41 PM

#187 Scott Hawley. This is a good question, Scott–I hope I have an answer that will satisfy you.

First of all, be aware that in order to get 4 Btu (or kjoule) of ethanol, you need to spend, by most accounts, about 3 units worth of fossil fuels in the form of fertilizer, pesticides, and mostly diesel fuel for planting, harvesting and transportation.

Distillation requiring either fuel or steam is also an important component of this. These inputs represents lot of “uncaptured” CO2 emitted to the atmosphere in the overall balance.

In describing the combustion process, I’m going to use cellulose as an example of which ethanol is a slightly enriched derivative.

Cellulose is a “carbohydrate” which means “hydrated” carbon (chain). It can be viewed as a chain of carbon atoms with H2O “ornaments” attached to each carbon. When you burn the cellulose (stover), essentially no energy is obtained as the H2O molecules are broken off. Energy is obtained by breaking both the the C-C bonds and O=O bonds in O2, and creating much stronger (double) O=C=O bonds. Nearly all the energy liberated by the combustion process is a result of this type of bond rearrangement.

Now, you would like to sequester the CO2 after combustion. While you a right in saying that we know “how” to do this, it is somewhat energy intensive because an absorbent or adsorbent is generally used to separate CO2 fromt the flue gases, which later has to be regenerated using even more energy. Enough so that the 1 Btu margin you got from growing the corn and making ethanol out of it would essentially be annhialated. IMO, you would be better off partially oxidizing the cellulose, producing “char” for sequestration, and burning the modest amount of off gas for energy. You would have to count enriching the soil as part of the “benefit” in order to justify doing it this way.

Hope that helped.

April 9th, 2008 at 12:03 AM

Frank,

(#184) There are efforts to develop synthetic sieves but what is used on the space station is natural zeolite. The space station gets free vacuum so they don’t have to pump to get the CO2 back out. But, pumping seems to minimize energy requirements compared to the chemical methods you’ve been describing for application here below. Here is a report characterizing the material used on the space station: http://hdl.handle.net/2060/19980237902

Chris

Dylan:

April 12th, 2008 at 12:45 AM

Would air capture work well in road tunnels, I wonder? Presumably the CO2 concentration inside road tunnels is much higher than in the atmosphere generally.

Just a thought…

Harold Ford:

April 12th, 2008 at 11:23 AM

This is a follow up to #96.
The main idea is to not find new ways of doing anything but to tweak the current processes. The advantage is that we experiment very little on our atmosphere while removing higher percentages of CO2 and natural gas, re-storing carbon in the ground, approximately as it had been before.
Experimenting is done on a small scale then prototyping. If the prototype doesnt come out right, scrap it. You cannot scrap the Earth and get another, not now at any rate. Reckless I think is the word I’m looking for. Just the scale of the assumption that it would work perfectly and not add too much or take away too much of whatever gases is mind boggling. Keep experimenting, of course, on a small scale, just try it on Mars or Venus first, that way we can look at the results from a distance. If the Earth was really bad off, we needed personal oxygen supplies etc, then doing it here wouldnt be such a bad idea.
I like the Moringa tree idea Lynn, not sure about the amount of Carbon it absorbs from the air but it sounds like it should be alot compared to other trees (doesn’t take it from the ground, where else would it get it from but the air?). Phil, the idea of ocean going plants and/or organisms eating the CO2 and then sinking after death is a good one, wish I’d thought of that lol. How would we control their growth, once the job was done?

Andy Siebert:

May 2nd, 2008 at 2:31 PM

There are so many wonderful posts already discussing possible solutions to this CO2 dilemma. I especially found value in comments 13 (thanks Jim) and 9 (thanks Bernie): planting more trees makes a lot of sense to me too, though I understand with their decay they release much of the C02 they stored. Many solutions have been discussed by people more articulate on the subject than me. However, I notice something relatively obvious to me isn’t being discussed.

While we ponder solutions to the dilemma in so many ways, what about pondering the dilemma itself? Consumption is the source of the release of CO2. One of the easiest ways to PREVENT the release of CO2 is to reduce consumption. Unfortunately, we built the foundation of our industrial economy in such a way that consumption appears hardwired into the root of the equation. What if there’s another way?

The cost prohibitive factors of CO2 re-sequestering (following release from a previously stable source) will always be less efficient than NOT RELEASING these gases in the first place. Alternative fuels, better/more efficient technology and processes merit continued focus, but what can be done to shift the trend of consumption?

I realize this video is a bit simplistic but that’s part of what I like about it: http://www.storyofstuff.com/ is accessible/understandable to anyone. We must remove the incentive for planned obsolescence. Why mine, transport, manufacture, assemble, and again transport materials for entire new machines when only a fraction of parts are actually being upgraded? There’s waste at every step of this process. Even as “retro” becomes increasingly trendy, you don’t see an influx of “antique computer repair” shops opening up everywhere. A universal motherboard with upgradeable components isn’t hard to conceptualize: but the manufacturer can’t justify selling you a $1,000 processor unless it comes in a shiny new computer… The first cellphone I ever bought was the most reliable I’ve ever had, but I’ve been FORCED to buy 5 in 10 years due to the manufacturers no longer “supporting those devices”. This trend puts us on a crash course when we’re already in a tailspin.

The irony is not lost on me that I say I’m forced to consume a product that hasn’t existed for the span of my life on this planet. But my point is that we need to shift the incentive away from encouraging companies to continually create waste by continually making products that are only slightly better, when it makes more sense to reward them for upgrading existing products. This doesn’t even touch on the e-waste issue, which is beyond the scope of this article but can’t escape mention.

The first step in this process is with the consumer’s perception that “new = better”. This would create a consumer base that would support financial incentives for companies to provide upgrades instead of entirely new products, and we could substantially reduce emissions and also save costs which would otherwise be spent sequestering the waste of this production. The incentive has 2 components: STOP rewarding waste, and START rewarding expandable products.

Hank Roberts:

May 2nd, 2008 at 6:06 PM

I grew up repairing most anything and still try.
But it’s amazing how hard it is nowadays.

And — compare the insides of a lamp socket made a few decades ago, next time one fails, with what you can buy to replace it. The new stuff can’t last anywhere near as long as the old did; thinner, more fragile, cheaper. Always.

Harold Ford:

May 2nd, 2008 at 7:43 PM

Hi Andy 193
I was curious to see if I had the last word on this topic and looked in. CO2 is released by the decay of trees. However, if you store the debris in a container that has no oxygen, you get CH4. That in mind, if you have CH4, you have another greenhouse gas but one that is burnable and stored in said container, the whole crux of the issue. So, everything is still stored and not released into the atmosphere until it is burned for such things as heating and/or electricity. The gas would change to H2O and CO2 as usual after burning however that means that other forms of fossil fuels were not used. A plus here is that it naturally scales itself to the size of the civilization that produced it. Whether or not it produces enough energy is a question that can only be answered through simulation or actually doing it. I’m in favor of doing it as we have nothing to lose and much to gain (in comparison to the current system).

May 3rd, 2008 at 6:21 PM

The dispersal of pulverized olivine I recommended here earlier is also recommended by Prof.dr. Olaf Schuiling,
Universiteit Utrecht:

19 June 2007

Geochemical CO2 sequestration – to save the world (in case the world needs any saving)
Outside the group of earth scientists it is rarely realized that chemical weathering is the major pathway by which CO2 is removed from the atmosphere. Enhanced weathering increases the rate of removal. This can be achieved by mining and crushing large quantities of olivine, and spreading the olivine powder over the land surface, or in the high energy zone of coastal waters…

Hank Roberts:

May 3rd, 2008 at 10:11 PM

And it’s been looked at for going on a decade now. Something about the spam filter won’t allow me to give you cites to the work done over the past decade on this, but look them up:
olivine+chemical+carbon+dioxide

Arch Stanton:

May 4th, 2008 at 9:41 AM

Hank (197),

I have also heard encouraging things about olivine/serpentine CO2 sequestration. When I put “olivine+chemical+carbon+dioxide” into Google Scholar I find few hits within the last decade and few that are discouraging. Outside of the obviously significant problems of serpentine being found in geologically active areas, and the energy intensiveness of the process of sequestration, what other problems are there? Perhaps a name would help my search?

Thanks, Arch

Hank Roberts:

May 4th, 2008 at 10:54 AM

Dumping a slurry into the ‘active coastal waters’ where mixing would happen likely wipes out most of the base of the marine food chain, and the method is very slow at standard temperature and pressure.

The work I found published, as you note mostly a decade or so ago, described olivine reactors efficient as closed systems with high temperature and high pressure. That’s expensive.

Price of fuel has gone way up since then. Perhaps siting something like this where it could use waste heat from power plants makes sense.

May 4th, 2008 at 3:15 PM

Dumping a slurry into the ‘active coastal waters’ where mixing would happen likely wipes out most of the base of the marine food chain

That would not be the objective. As I said above, each 100 gigatonnes of legacy CO2 in the atmosphere would convert to a few hundred km^3 of dust. If this were deposited over tens of millions of km^2 of dry desert, or hundreds of millions of km^2 of a wet desert such as the southern ocean, it would be unobtrusive.

Understand that the accumulation would be over a decade or so. It would not arrive all at once as a layer 1 cm thick on the tens of millions of km^2 of land, nor as a 1-mm layer on hundreds of millions of km^2 of sea.

You’re the first to speak of a slurry. Per mole of legacy CO2, the creation of which mole yielded about 400 thermal kJ if it was in a coal furnace, 20 kJ would be needed for comminution. I had in mind that another 20 kJ/mol could be used to lift the olivine powder 10 km above ground level so that it would be well dispersed when it came down.

… and the method is very slow at standard temperature and pressure.

It’s quick enough — four years for forsterite grains of which 80 percent pass through a 100-micron screen, fewer years for olivine with a significant fayalite component. BTRO.

(I believe fayalite does not sequester any CO2 itself, but its iron’s oxidation from II to III helps break up the rock. So a few parts in 20 is helpful, even if it increases the required amount of olivine, because it allows the same speed with less comminution energy input.)

Hank Roberts:

May 4th, 2008 at 7:05 PM

Well, there’s a lot, a whole lot, online about the idea.
Let’s see if this will be allowed by the paranoid spam filter:

Status of Research Effort
Preliminary evaluation of reaction paths:

−MgCl2 Molten Salt process (found unreactive)

−Direct Carbonation using supercritical CO2 and water at elevated pressures and temperatures
(found promising)
———- end excerpt———–

That’s from 8 years ago.

Frank Zeman:

May 5th, 2008 at 8:21 PM

#191 Dylan – you’re right that CO2 levels would likely be elevated in a tunnel and if you have ventilation shafts then you have a nice access point. The advantage of air capture is you can site it where you want, which avoids trying to get pipelines through urban areas etc. The slight elevation in CO2 would only help if the CO2 transport was not significantly harder.

#193 Andy – absolutely, it’s much easier to not create the problem then have to solve it after the fact. If you look at Pacala and Socolow’s wedges, you’ll notice efficiency as a big player.

as for mineral sequestration. There is work at columbia and my understanding is all of it occurs at high CO2 pressures (20 atm) so any atmospheric usage, like spreading in the desert, might have kinetic barriers. On the other hand, if it does the job in 100 years that’s fine as long as it’s not covered by blowing sand.

May 6th, 2008 at 6:52 AM

so any atmospheric usage, like spreading in the desert, might have kinetic barriers. On the other hand, if it does the job in 100 years that’s fine as long as it’s not covered by blowing sand.

And what would happen, Frank, if olivine grains were covered by blowing sand? No doubt you did not miss, nor find fault with, my above figuring that the slowest-acting olivine variant would, in 100-micron-screened grains, be consumed in four years.

Are you figuring that 30 cm of overlying sand would add 96 years of diffusion time?

Harold Ford:

May 6th, 2008 at 12:07 PM

Ok, so maybe I’m not the brightest bulb here but there has to a product to this: CaMgSiO4 + CO2. I’m only guessing at it but I hope the product would be Dolomite CaMg(CO3)2 and sand. There are several other products it could be and hopefully it wouldn’t be Calcite or Magnesite. If the process only produces dolomite and sand then I’m a fan of this idea otherwise what exactly is the end product?

Hank Roberts:

May 6th, 2008 at 2:34 PM

Watch out for the asbestos fibers, better not put anything containing that in fine particles where the wind blows. Mine tailings have a lot of issues, but clearly people are working on this notion eagerly. Any opportunity to turn a hazardous waste problem into a carbon dioxide sink is going to be attractive.

Frank Zeman:

May 6th, 2008 at 9:00 PM

To GRL Gowan:

My comment was more general that your detailed calculations in post 151. The 100 years referred to a generic time scale to solve the CO2 problem as the technology of spreading magnesium silicates in the desert can be termed a passive technology. The 4 years you refer to is called “weathering”. Does this refer to size reduction or dissolution? In your early quote regarding mine tailings you mention that the reaction is aqueous, which would not happen in a desert. As for the 30 cm, I’m not sure where you got that number but yes the gist of the comment was that if the magnesium rock is buried then it will react more slowly. My only trip to the Morrocan desert included tales of 30ft high dunes moving around. I’m sure there are other deserts that are more flat (Altacama). It was a more general comment. In what I’ve seen of mineral sequestration, the initial effort is usually to get the magnesium ion into solution as gas solid reactions are much slower. Again, everything I’ve seen has involved CO2 pressures of 20 atm not 400 ppm. Doesn’t mean it won’t work though. Just thoughts.

peace
Frank

Harold Ford:

May 8th, 2008 at 1:58 PM

Found this pdf article dated 2001 which covers this topic that I found meaningful:

The article mentions that olivine reacts slowly with CO2 in an exothermic reaction. It also mentions that a few things were done to speed up the reaction at Los Alamos so that scrubbing of a coal plant’s CO2 could occur. Turns out that what they did increased efficiency by 25% from the norm (whatever the norm is). Seems like simply increasing the amount and surface area of Olivine would do the trick for scaling the amount of CO2 reacted per unit time. Second trick would be to find enough Olivine, someone mentioned Washington State. The final trick would be sequestering the Magnesium Carbonate, as leaving it out to be weathered means that it could release the CO2 through contact with acid, getting blown into the ocean wouldn’t help.

May 8th, 2008 at 7:30 PM

Seems like simply increasing the amount and surface area of Olivine would do the trick for scaling the amount of CO2 reacted per unit time. Second trick would be to find enough Olivine, someone mentioned Washington State. The final trick would be sequestering the Magnesium Carbonate, as leaving it out to be weathered means that it could release the CO2 through contact with acid, getting blown into the ocean wouldn’t help.

But neither would it hurt. Magnesite is stable. The reaction of atmospheric CO2 and olivine — whose occurrence you can find discussed under the name “dunite” — goes only one way.

So we haven’t found a perpetual motion mechanism, but at least we can deal with CO2.

May 12th, 2008 at 8:22 AM

Talking of ‘Air Capture’, wouldn’t it be economical and chemically efficient to capture concentrated CO2 from stacks by having the stack gases pass through a disk-shaped sponge or other porous matrix impregnated with calcium oxide/iron oxide and a catalyst? The resulting CaCo3/iron carbonate ‘disk-shaped bricks’ could be easily disposed off, or if rigid enough, used in selected constructions. (Can we count on PM2.5 to catalyze the reaction?!!!)

Hank Roberts:

May 12th, 2008 at 8:56 AM

> , but at least we can deal with CO2.
But nobody’s interested in doing this. Is it because of the asbestos problem, do you think?

May 12th, 2008 at 4:29 PM

But nobody’s interested in doing this. Is it because of the asbestos problem, do you think?

Leading question. No asbestos problem has been shown to exist with olivine. There may be one with serpentine, if asbestos-free deposits of it are for some reason hard to find.

Appeal to authority, and falsehood. I’m interested and so is the professor-doctor I mentioned. Prof.dr. Olaf Schuiling.

It might be rather boring. What if no further research were nee–

were nee–

What if further research were not, not, ah, … well, you probably know what I’m getting at. You try and say it.

Hank Roberts:

May 12th, 2008 at 7:13 PM

I’m just asking why I can’t find anything new about the idea, it seems to have surfaced some years back and been evaluated and dropped. Where are you seeing interest?

richard schumacher:

May 13th, 2008 at 9:11 AM

The observed rate of increase of atmospheric CO2 indicates that natural sinks of CO2 cannot absorb more than about 20 billion tonnes of human-created CO2 annually. The world’s current rate of use of fossil fuels creates some 30 billion tonnes of CO2 annually, or an excess of roughly ten billion tonnes of CO2 annually, equivalent to 5000 cubic kilometers of gas (1200 cubic miles) of gas or 80 cubic kilometers (20 cubic miles) of liquid at 60 bar (nearly 60 atmospheres) pressure. Assuming no change in the use of fossil fuels, halting global warming would require capturing, handling and storing that much CO2 every year, forever. The sheer scale of this effort looks infeasible, and it may be physically impossible.

Assuming the low end of the costs anticipated by the Department of Energy for its sequestration demonstration projects ($40 to $100 per tonne of CO2 sequestered), attempting this apparent impossibility would cost four hundred billion dollars per year. But notice that this is equivalent to nearly $150 per tonne of carbon sequestered. A fossil carbon tax of $50 per tonne with the proceeds invested in non-fossil energy sources would be far less expensive and more easily implemented, and would start reducing CO2 emissions more quickly than could any feasible sequestration effort.

Note that none of the above invalidates the feasibility of the work by LANL on capturing atmospheric CO2 to manufacture artificial carbon-neutral liquid hydrocarbons for vehicle fuels:http://www.lanl.gov/news/index.php/fuseaction/home.story/story_id/12554
The goal of that work is to eliminate the need for petroleum and coal-to-liquids (CTL) fuels, both of which contribute to global warming.

Two ideas have been mentioned: reacting mineral silicates in some kind of pot, which as you say would be expensive, and reacting them outdoors.

Have you seen any dropping of the latter idea?

… 80 cubic kilometers (20 cubic miles) of liquid at 60 bar (… halting global warming would require capturing, handling and storing that much CO2 every year … looks infeasible, and it may be physically impossible…

I don’t know if Schumacher will resist the idea that it’s a lot easier if the capture occurs at widely dispersed dustmotes’ surfaces, and nothing need subsequently be done with the captured CO2.

But a lot of people in this thread seem to wish to overstate the difficulties. At least the thermodynamic bluffers seem to have quit. For the moment. Maybe they slid away on a conjugated sub-entropic gradient.

Hank Roberts:

May 13th, 2008 at 4:44 PM

Nope, I’ve seen no recent mention of either idea except yours. That’s why I was asking where you’re seeing it.

Frank Zeman:

May 13th, 2008 at 4:49 PM

#209 – That has been considered and is termed capture with solid sorbents. If you want more information look up anything by a spanish researcher called Juan Carlos Abanades. You are right to mention capture from power plants and other large stationary sources that will be likely easier and cheaper than Air Capture. The standard technology is wet scrubbing using a chemical called MEA. MEA is considered better than lime (calcium oxide) because it consumes 40% less energy (140 kJ/mole CO2 for MEA versus 200 kJ/mole for lime) and needs energy at much lower temperatures (200oC for MEA versus 900oC for lime). It’s important to remember that you can’t dispose of the product (CaCO3) because you had to make it in the first place. Lime is made from limestone so if you dispose of it as limestone again then you’ve lost something because “you can’t get something for nothing”.

#213 The natural capacity you are referring to is the ocean. There is a price for letting the ocean absorb all our CO2 and that is acidification. That’s out of my area but I have not heard good things about it. The oceans are already being challenged so it’d may be nice to reduce the CO2 they have to absorb. As for the amount of material, yes its big and really we should be aiming at getting maybe 10 billion tonnes of CO2 using CCS with as big a portion from efficiency and renewables. See wedges.

#214 Again, I’ve not said that reaction between atmospheric CO2 and magnesium silicates is not possible but you have to provide evidence that the time scale, naturally geologic, can be accelerated to less than 100 years. I’ve not seen any experiments done with atmospheric CO2 pressure. Thermodynamics tells you where it will eventually end up but nothing about how fast it gets there.

May 13th, 2008 at 10:24 PM

… you have to provide evidence that the time scale, naturally geologic, can be accelerated to less than 100 years. I’ve not seen any experiments done with atmospheric CO2 pressure. Thermodynamics tells you where it will eventually end up but nothing about how fast it gets there.

Atmospheric CO2 pressure and olivine are both ubiquitous, so nature can hardly have refrained from doing the experiments. Earlier when I searched, IIRC, on (olivine “weathering rate”) I found that the rate has been measured. Hmm, I see I gave that Velbel link before, but with a comma that made it not work.

Zeman asked earlier, “The 4 years you refer to is called “weathering”. Does this refer to size reduction or dissolution?”

Velbel’s Figure 1 gives it in terms of moles per square-centimetre-second, which can be converted, as I did in comment 151, into a recession rate; this does not refer to, and is independent of, size reduction, aka comminution.

Comminution is a job, not for the weather, but for us. It costs about five percent as much energy as was earlier yielded when the CO2 we’re after was released, if a coal fire in a power plant released it.

For magnesium orthosilicate, the slowest-weathering variant of olivine, Figure 1 gives 7.9e-13 moles per square-centimetre-second. Comminution will allow a mole to be eaten in significantly less than a century, i.e., to have a weathering rate significantly above 3.2e-10 moles per second, through having significantly more than (3.2e-10/7.9e-13), significantly more than 400, square centimetres of surface.

Frank Zeman:

May 14th, 2008 at 11:40 AM

I guess I’m still missing something. Does the rate of weathering refer to the release of Mg2SiO4 into the environment or does it refer to the conversion of Mg2SiO4 to 2MgO and SiO2? The latter step is the reason acids and other chemical weathering techniques are used in mineral sequestration research.

I agree that mother nature is doing the atmospheric experiments for us. The lifetime of CO2 in the atmosphere is 200 years which suggests that that is the relevant kinetic time frame for natural processes. The objective of mineral sequestration is to reduce this time frame by two orders of magnitude. So if you grind it up (agree that grinding is about 5%) and spread it (another 5%?) then what happens? If the next reaction is Mg2SiO4 + 2CO2 > 2MgCO3 + SiO2 then my hunch it’s still too slow.

Using the rate of 8e-13 mol/cm2/s, which can be converted to 1e-5 tonne/m2/yr, we can calculate that about 0.1 km2 are needed to absorb 1 tonne of CO2 in a year. So in order to handle 7% of the global problem (1 wedge) we need to cover 200 million km2 of earth considering a monolayer of material. I assume that a monolayer is not necessary but don’t have any numbers for the allowable depth. Given that the land area of the US is 9 million km2 that’s a lot of area.

May 15th, 2008 at 9:28 PM

200 million square kilometres is more land than there is. If depositing the monolayer were possible, 200 million km^2 of sea surface might be a good place for it, although it would break into particles, and if these settled into the depths too quickly, they would decarbonate places where our CO2 hasn’t yet reached, and not the places where it has.

Rather than a monolayer, what I had in mind was more along the lines of a crusher that, per mole of targeted CO2, uses 20 primary kJ to crush rock and another 20 primary kJ to power a conveyer that throws the powder vertically upward with an initial kinetic energy of 7 kJ.

This is enough, if it’s a broad stream that at first feels little air resistance, to lift it ~10 km. The proper stream would be narrow enough that the air it was flying through would have picked it apart by about the same time it would be coming to a halt, and it could then ride a trade wind while it settled.

Does anyone know, or can anyone find, a Bond work index for dunite or olivine? I could not, so am continuing to use 25 kWh/tonne, which is probably high.

The Bond work index is the work of comminution from large pieces down to 100-micron ones. The latter sink about 1 m/s in air.

Doubling the energy invested in comminution from 20 kJ to 40 kJ — per mole of targeted CO2 — reduces the particle size fourfold, down to 25 microns, and reduces their sink rate 16-fold. This is probably worth doing, even though it raises the invested energy to 50 kJ. (It also reduces the particles’ lifetimes with respect to reacting with atmospheric CO2 from four years down to one year.)

The mentioned 200 million km^2 of surface area is that 10^23 spherical 25-micron particles, volume 833 million m^3.

Can these be strewn widely enough to mix with ten times their volume of naturally blowing dust, and still make a fairly thin layer? 9 km^3 of mixture, if it is to be a 1-cm layer, will cover 0.9 million km^2.

CO2 has to percolate the 1-cm layer, but I guess a year is plenty of time for it to do that, and therefore I believe this is a better arrangement than the 200-million-km^2 monolayer.

Frank Zeman:

May 16th, 2008 at 10:46 AM

That’s a neat way to spread it. I think the grinding number is right, the cement industry is a bit lower at 16 kWh per tonne. I guess it should be easy to try that and measure the CO2 uptake.

May 18th, 2008 at 7:35 AM

Olivine to remove CO2 from the atmosphere.
I have probably been the first (1986)to use olivine to neutralize waste acids. Olivine is the most common silicate in the Earth, and it is available in large massifs in many countries, where it can easily be mined in open pit mines. Rate of weathering depends mainly on grain size, temperature and pH. Weathering of basic silicate rocks (olivine is the most proiminent basic silicate) removes between 2 and 2.5 Gt of CO2 each year from the atmosphere. That makes weathering by far the most important mechanism for capturing CO2, with burial of organic carbon a distant second. In order to reach a new balance, we must speed up the weathering of olivine by a factor of 10. This can be done by opening new olivine mines in tropical countries, where weathering is fastest. There the olivine rock must be ground and spread in the wider surroundings of these mines. These new olivine mines will be larger than existing olivine mines, so the economy of scale will drive the price down. Transportation cost will be low, because the material will not be transported more than a few hundred kilometer from each mine. Calculations show that the price will be around 10 to 15 US$ per ton of captured CO2, say 5 to 10 times cheaper than other proposals like carbon capture and storage. Moreover, this approach will bring new employment to developing countries.
The reaction is often misunderstood. The products are not solids, but dissolved Mg- and bicarbonate ions, that will find their way by passing through groundwaters and rivers. They will help the oceans to counteract the ongoing acidification. We are developing now a simple technology to keep fine-grained olivine floating on the surface of the sea. A large field test with olivine has started this week in the Netherlands. The theory behind the enhanced weathering concept can be found in:Schuiling, R.D.and Krijgsman (2006) Enhanced weathering; an effective and cheap tool to sequester CO2 . Climatic Change, 74, nrs 1-3, p.349-354. A proposal along these lines has been submitted to Virgin Earth Challenge, for the best idea to remove 1 bliion tons of CO2 from the atmosphere.

Hank Roberts:

May 18th, 2008 at 11:39 AM

This is on the broader topic of dealing with GHG emissions from “small, dispersed sources” — here’s a source being warned of. I don’t know anything about the website, it says it’s an independent journalism source.

Question (not addressed in the article I found) — are refrigerated shipping containers still being made using new CFCs, being made new in the countries that have longterm exemptions? Or are those complained of only old contaniners still in use from before the phaseout?

Excerpt follows:

Published Date : 09-20-07
Reefers: Not Smokin’ but Leaking GHGs
Old Refrigerator Shipping Containers Called Major Source of Greenhouse Gases

“… a loophole. According to the California Air Resources Board, that loophole allows shippers to discard a hundred thousand worn out reefers [refrigerated ocean shipping containers, the huge metal boxes you see on ships] a year in Wilmington and other communities under the guise of long-term storage. By so doing, they are evading requirements to properly recycle or dispose of the harmful chemicals.

…
“…[t]he California Air Resources Board [has been asked by citizens’ groups] to require shippers to drain the chemicals … [CARB plans] to look at the problem in the context of a revised list of early action measures to control greenhouse gases under California’s climate protection law, AB 32. In its revised list, the board is planning to study the potential problem….”

—–end excerpt—–

This kind of GHG isn’t susceptible to “air capture” at all, and is a serious forcing.

May 18th, 2008 at 3:38 PM

It is said to show the massif’s “east contact”, by which I gather it means where it contacts non-olivine terrain. The boundary can be very plainly seen: olivine is ferric orange, non-olivine is plant green. Olivine massifs tend to be low in Ca, Na, K, P, and B, and therefore, as someone, probably Dr. B.M. Gunn, says here,

no vegetation grows on them, but they are not “toxic” as often reported, merely deficient in essential elements.

An interesting commercial it claims that a process exists that can combine CO2 with Calcium Silicate + H2O + 15min and get limestone:

Ty GRL (#208 Magnesite is stable) just had to verify it. I am remembering an article of some experiment concerning the running of (CO2 free) water over said Magnesite + Heat causing it to change into Brucite:

Unlikely as that may seem to pose a problem as Magnesite is part of the oceans’ long term carbon cycle, could it pose a problem on some ecological order, assuming large quantities of Magnesite exposed to air randomly assaulted by weathering over large quantities of time? I pose this only because man has gone through countless “Ah hah!” moments only to find more problems caused by the solutions implemented thus causing a confused (standard?) “Ah hah?” response.

June 3rd, 2008 at 9:48 PM

… the running of (CO2 free) water over said Magnesite + Heat causing it to change into Brucite:

The paper tells how much heat:

MgCO3 + H2O⇌Mg(OH)2 + CO2 began at about 150° C.;

I gather from Felton’s silence that he does agree, but does not wish to seem agreeable.

Harold Ford:

June 4th, 2008 at 11:12 AM

This idea has been around awhile and knowing theoretically what would happen if we did use olivine would help decide whether or not to use it in this way. Could a computer simulation be set up or an experiment be done? As I recall there is a large building somewhere in the western US deserts that was supposed to simulate a livable Earth like environment, a failed experiment that was a stepping stone to live on Mars (vegetation thrived but animals died, seems there is a micro-organism in the the desert that devours oxygen). The last I heard of it it was being used to conduct weather experiments. It’s name is… I forget but it does exist and it does not sound like it would be too much trouble to convince someone to use it.

June 4th, 2008 at 7:19 PM

A large field test with olivine has started [the week of May 18, 2008] in the Netherlands.

Hank Roberts:

June 4th, 2008 at 8:41 PM

Harold, you’re thinking of Biosphere II. Not likely usable.

Phil. Felton:

June 5th, 2008 at 1:22 AM

Re #228

“In words, that extra mole of CO2’s removal would be a bonus, and perhaps we don’t get it, but to the extent we don’t get it, we get a reduction in ocean acidity instead. Do you agree?”

No the relationship between CO2 and [HCO3⁻] is given by the equation I gave above, it doesn’t matter how the CO2 or HCO3⁻ got there:

pCO2=K2 [HCO3⁻]^2/(K0 K1 [CO3⁻⁻])

“I gather from Felton’s silence that he does agree, but does not wish to seem agreeable.”

A very dangerous assumption, in this case the silence was due to travelling and not seeing the post until today!

Harold Ford:

June 5th, 2008 at 9:11 AM

From #221 (ty GRL) Dr. Dirk Schuiling, it is a process of improving the ability of weathering to remove CO2 but olivine does not react with the gaseous form of CO2 w/o H20 *hits head*.
(from #221)
A proposal along these lines has been submitted to Virgin Earth Challenge, for the best idea to remove 1 bliion tons of CO2 from the atmosphere.
#
Ok, my hair brained scheming has come up with a plan for that challenge and that has to do with plants (of course). But not just any plants, plants that can absorb CO2 directly from the air, just add water. Rather than waiting for rain, these plants would have a water supply close by and continuously devour CO2. What plants? not sure, it would seem to me that a shallow rooted plant that does not deplete the soil of mineral content would be the choice. A plant that can be used to make clothing, sail boat sails, rope, medicene, building material and/or food would be good. However we cannot save the world with an illegal substance, that would be wrong.

Harold Ford:

June 6th, 2008 at 4:52 PM

Ok, jokes aside. Let’s say we have a plot of land that is 100 m^2. On this land we put hypothetical plants that gain weight at a rate of 4 grams a day per plant and that it takes 0.1 m^2 to support one plant therefore 1000 plants. Baring the explanation of upkeep and harvesting, the total that these plants absorb is 4kg per day 6CO2+6H2O = C6H12O6+6O2 for photosynthesis means that (264/180*4kg) 5.867kg of CO2 was absorbed from the air. Now the challenge is to use the same amount of land using olivine (or other mineral) to estimate the amount of CO2 absorbed through weathering. Using Washington States annual rainfall gestimate 900ml over an area of 100m^2 gives a 90m^3 amount of rainfall for Seattle comes to a weight of (1000kg/m^3) 90000kg of water. Not sure but lets use 2 parts CO2 for every 1000 parts water or 180kg of CO2 possible for one year… 5.867kg/day * 365 days = 2141kg CO2/year for the hypothetical plant while 180kg for the hypothetical 2000 ppm CO2 to H2O rainfall over olivine. It would seem the plants win at 2000 ppm and would be equal at 23789 ppm?

Thanks Hank (#233) for the Biosphere II info.

November 25th, 2008 at 12:01 PM

Now, you would like to sequester the CO2 after combustion. While you a right in saying that we know “how” to do this, it is somewhat energy intensive because an absorbent or adsorbent is generally used to separate CO2 fromt the flue gases, which later has to be regenerated using even more energy. Enough so that the 1 Btu margin you got from growing the corn and making ethanol out of it would essentially be annhialated. IMO, you would be better off partially oxidizing the cellulose, producing “char” for sequestration, and burning the modest amount of off gas for energy. You would have to count enriching the soil as part of the “benefit” in order to justify doing it this way.

Patrick 027:

March 30th, 2009 at 6:19 PM

Re 221 – “Weathering of basic silicate rocks (olivine is the most proiminent basic silicate) removes between 2 and 2.5 Gt of CO2 each year from the atmosphere.”